RADIATION ONCOLOGY
Authored by Dr. Stephanie E. Weiss
Historically, radiation oncology has been one of the best kept secrets in medicine. Yet the specialty has of late become one of the most competitive fields for entering applicants. Radiation oncology is an intellectual discipline with physician-patient relationships at its heart. Its strength and appeal lies in the multidimensional approach to treating cancer patients.
Paradoxically, as popular as the field has become among medical students, radiation oncology remains poorly understood, even by other physicians. Radiation oncologists, who are embedded within the interdisciplinary practice of cancer treatment, play a role as both primary oncologist to cancer patients and as consultants to other physicians. It is a field that weds the physician's breadth of knowledge to the meticulous application of technical expertise. Every cancer patient, after all, offers an individual challenge.
RADIATION AS CANCER TREATMENT
Radiation oncology is the specialty of medicine that uses radiant energy for treating malignant disease (cancer). For most physicians, it is easy to think of prescribing a medicinal substance in terms of administering a certain number of milligrams of a drug, delivered perhaps orally or intravenously. Chemotherapy fits intuitively into this category. Yet it is not as obvious to think of radiation as a prescription, too. Radiation is invisible. It is not typically administered by vein or mouth, but rather by complicated equipment that may not even touch the patient's body.
Radiation, usually in the form of photons and electrons, works therapeutically on the molecular level by principles similar to other treatment modalities such as chemotherapy. The killing of cells by chemotherapy is induced by chemical substances, while radiotherapy inflicts similar damage through radiation. Specifically, radiation works by interfering with the cell's ability to reproduce successfully. It takes advantage of the fact that normal cells can repair radiationinduced DNA damage in between daily small-dose treatments, whereas a cancer cell cannot.
It is the responsibility of the radiation oncologist to prescribe the proper dose of radiation. Measured in the unit of Gray, the amount of radiation administered is based on the tumor's radiosensitivity as well as the specific tolerance of nearby normal tissues to radiation. Treatment is adjusted accordingly to cause maximum damage to cancer cells while keeping normal tissue within its tolerance. These specialists have a good understanding of how changing the daily dosage or overall length of treatment optimizes these clinical benefits. The difference in susceptibility to radiation between normal cells and cancer cells is called the therapeutic index. A skilled radiation oncologist manipulates each plan to take full advantage of this therapeutic parameter.
WHAT MAKES A GOOD RADIATION ONCOLOGIST?
Likes fast-evolving technology.
Enjoys an intellectual environment with an emphasis on scientific literature.
Can cope with treating patients who are terminally ill.
Enjoys being part of an interdisciplinary team.
Has an amiable personality.
THE TYPICAL DAY OF A RADIATION ONCOLOGIST
Those unacquainted with this specialty often make the mistake of equating the radiation oncologist's role to that of a technician. If you choose to practice radiation oncology, get ready for all manner of button-pushing witticisms. But your more earnest colleagues will often ask you to describe, in the most fundamental terms, what it is that you actually do as this type of doctor. Radiation oncologists do not press buttons any more often than medical oncologists (chemotherapy physicians) stand over a Bunsen burner preparing a concoction of some chemotherapeutic brew. Those who actually deliver the radiation treatment - the therapists - hold their own special position in the care of cancer patients, which is quite separate from that of the physician.
For a radiation oncologist, the care of a cancer patient begins with the referral for consultation. Radiation oncologists, therefore, take on the role of consultant, rather than primary, cancer care physician. You will receive patients from another member of the interdisciplinary cancer treatment team. For instance, an otolaryngologist who resects a malignant mass from a patient's neck may send that patient to you for additional treatment. Medical oncologists refer many of their patients with lung cancer or other malignancies to radiation oncologists for further management and specialized expertise. Radiation oncologists rarely receive patients directly from primary care physicians. This is mainly because a patient must first be diagnosed with cancer before they wind up with any oncologist. Sometimes the way to your clinic is even more serpentine, in part because radiation oncology simply remains a hit of a mystery even to other physicians. Some patients tread a tortuous path before they find their way to the radiation oncologist, which illustrates the value to both you and the patient of having a learned referral base.
At the initial consultation, you will perform a history and physical examination that, in keeping with the academic nature of this specialty, is rather inclusive. Radiation oncologists are fluent in their diagnostic skills. Any patient under medical care needs observation for sequelae of disease and effects of medical intervention. Cancer patients are quite prone to a host of systemic problems from the outset. Because patients receive treatment in clinic every clay, the radiation oncologist often diagnoses many medical problems while the patient undergoes treatment. A keen diagnostic eye and reasoned mind is a must.
During this consultative appointment, emphasis is placed not only on the particulars of the patient, but on prior or planned therapy and other diagnostic information. You must be well-versed in relevant surgical procedures, radiographic images, and pathologic variants of disease. At consult, radiation oncologists have a considerable amount of information to correlate to achieve a complete clinical picture and come up with a cogent treatment plan: Was there total gross resection? Were the margins microscopically positive or was tumor trailing along a nerve bundle? Was there an operative tumor spill? Compression or invasion of other organs will also be taken into account. All radiation oncologists must consider anatomic involvement as defined at surgery and then compare it with findings from diagnostic imaging.
Further testing and clinical investigations are an important part of practicing radiation oncology. Radiation oncologists direct the overall plan for their patient by ordering whatever additional diagnostic studies are needed. Comprehensive skill at diagnostic techniques, therefore, serves you well in this specialty. In particular, the ability to interpret radiographic and nuclear images is vital. After all, radiation oncologists have to scan for the presence of disease that may have been missed by the surgeon's eve but is still important to encompass in your radiation port. For instance, when viewing a lung mass on CT scan, you will play an integral role in complex diagnostic considerations. Is that all tumor which needs to be treated, or perhaps there is associated consolidation, which could represent an area of lung that your treatment might spare? For the medical oncologist, this may be less of a consideration if it does not affect their treatment plan. But for the radiation oncologist, it may have significant impact. You may end up ordering, for example, a functional imaging scan such as positron emission topography (PET) - a new way to look at metabolically hot (and likely tumor-related) cells. Before initiating any radiation treatment, you may also suspect the presence of metastatic disease. Appropriate investigations, therefore, confirm or rule out your suspicion. Radiation oncologists need to understand the clinical behavior of the disease so that they can give the most appropriate treatment.
Radiation oncologists also require a solid understanding of the histology and pathology of cancer. Endometrial cancer, for example, is one of the common malignancies these physicians treat. For this disease, knowing the pathologic difference between high-grade and low-grade tumors could determine whether a patient should receive any radiation therapy. The expression of particular genetic markers and the depth of lymphatic or vascular invasion-two important diagnostic contributions from pathologists-may also guide the radiation oncologist's protocol. All of this diagnostic and treatment related information, plus any findings on physical examination, figure prominently in the decision whether to subject a patient to radiation treatment.
PLANNING RADIATION TREATMENT
For every radiation oncologist, the final treatment strategy is a personally designed plan of attack. Just as surgeons think about how they will approach an operation, radiation oncologists synthesize a great deal of information to come up with the best therapeutic regimen.
Radiation therapy begins with a simulation. During this phase, the oncologist uses techniques of fluoroscopy and CT scanning to localize the particular malignant area of interest. You analyze its relationship to normal and sensitive tissue structures so that they may be protected. Because tissues in the body all have a limit to the lifetime dose of radiation they can safely receive, treatment plans must always take into account this factor. This is where diagnostic imaging, pathology, and indeed the surgeon's narrative, come into play. Radiation oncologists incorporate all of these variables as they cone up with a treatment plan.
Because radiation oncologists expose the body to radiation (a foreign substance), the goal of therapy is to optimize the beam arrangement so that the prescribed dose reaches the tumor while minimizing exposure to normal tissues. Radiation oncologists work side by side with professional dosimetrists, who apply filters and change the relative weights of the beams to meet their specifications. (One can think of dosimetrists' role as parallel to that of pharmacists in medical oncology.) They make sure the correct dose of therapy gets to where you prescribed it. In addition, physicists are also on hand to verify that the plan delivers its dose.
Days later (sooner in cases of oncologic-related emergencies like spinal cord compression or superior vena cava syndrome), the patient is on the treatment table, ready to be set up in the same position as at simulation. The therapist aims the collimator (the tube which shapes the beam of radiation as it exits) and takes an x-ray (port film). The port film images the patient's bony anatomy, ensuring that the field in the beam's actual pathway is the same as planned during simulation. If the radiation oncologist thinks there is any deviation, the therapist shifts the patient in the appropriate direction. Once optimized, treatment is given. As you can tell, medical students interested in radiation oncology must have a firm grasp of gross anatomy.
RADIATION THERAPY: A MERGING OF BIOLOGY AND PHYSICS
Radiation oncology requires a solid knowledge of two important basic sciences: radiobiology and physics. Radiobiology is the study of the biologic and molecular basis for radiation therapy, such as the cellular response to radiation exposure in differing conditions and time schemes. You will learn how to select different types of radiation, choose appropriate energies, and calculate dose delivered to a patient. You will become familiar with a variety of isotopes used in the oncology clinic.
It is important not to let a bad experience with physics as a premedical student discourage you from taking a closer look at this specialty. The body of knowledge in both physics and radiobiology required for the radiation oncologist is not overwhelming, nor does it require a particular knack for the physical sciences. The vexing part of radiation physics, however, is simply that it is usually unfamiliar and daunting to undertake for the first time. Familiarity with physics is not necessary for medical students prior to entry into this specialty, because residency programs teach the required medical physics during the course of training.
For medical students with a bent toward either medical physics or basic science research, radiation oncology offers great opportunities. There are many laboratory experiments in radiation physics and dosimetry, as well as investigations in clinical oncology. Current trials include vaccines, cell sensitizers, and normal tissue protectors. These studies have already led to the use of medicines that protect the function of normal tissue from radiation preferentially over cancerous tissue. Even relatively recent research in radiobiology has now become the standard of care in treating specific cancers. For instance, today's radiation oncologist now has the option of applying radiation with novel therapies like hyperthermia and oxygen enhancers, in addition to combining radiotherapy with routine chemotherapy to increase its effectiveness.
Research and scholarly projects are an essential part of this specialty. First and foremost, radiation oncologists are oncologists, so all issues pertaining to the prevention, evaluation, and treatment of cancer are rich sources of investigational material. As a result, there is an abundance of clinical research-outcome studies, new forms of treatment, evaluation of developing technology-open to the radiation oncologist. For the serious academician, many multi-institutional groups have developed a host of randomized trials in which radiation oncologists partake in the development of treatment protocols. In 1999, the American Board of Radiation Oncology introduced the Holman Research Pathway, a residency-level initiative designed to foster interest in careers of basic science and clinical research. As you can tell, the laboratories within radiation oncology welcome all medical students interested in partaking in bench research and advancing the field of cancer treatment. No PhD is necessary to apply!
A HIGH-TECH SPECIALTY FOR HIGH-TECH PHYSICIANS
Today, more and more medical school graduates seek careers in radiation oncology. The specialty's surging popularity may have something to do with the fact that the first generation of doctors raised during the computer revolution is now graduating. Many technology-savvy medical students, who have grown up with both a compelling interest in and familiarity with technology, are drawn to the high-tech nature of radiation oncology.
There are many examples of radiation oncologists' use of the latest advances in medical technology. First and foremost, of course, is fractionation -the treatment method that takes advantage of the healthy cell's ability to repair a small amount of radiation damage (whereas a tumor cell is susceptible to destruction). In the 1930s, a group of French physicians observed that a single dose of radiation necessary to sterilize a ram caused prohibitive damage to the skin of the scrotum. By giving smaller doses of radiation for several weeks, they found that they could achieve their objective (sterilization) without producing any unacceptable skin damage. Based on these and later studies, scientists postulated that tumor cells were very similar to fast-growing germ cells and applied this model to cancer treatment in humans. Using fancy delivery systems, radiation oncologists today treat their patients with small daily doses of radiation for several weeks. Many fractionation schemes have been proposed with varying degrees of practical utility in the clinic.
New forms of technical experimentation are essential for improving the delivery of radiation. The major focus in research, of course, is improvement of the therapeutic ratio-killing only tumor cells while leaving healthy tissue intact. Back in the old days of radiation oncology, the technology consisted of easy-to-plan simple opposed beams of radiation, which are still common, useful, and practical today. However, with exciting developments in bioengineering, threedimensional radiation therapy is fast becoming the standard of care. Using computed tomography (CT)-based simulation, radiation oncologists apply multiple beams of high-dose radiation from many different angles-all within a three-dimensional plane. In the 1990s, another wonderful technologic development came along: intensity-modulated radiation therapy (IMRT). In this technique, thin sliding metal blocks (leaves) enter and exit a field of radiation for varying lengths of time. Both of these amazing forms of technology allow physicians to provide superior conformational coverage to the target. The end result is better protection of normal organ tissue and higher doses of finely shaped radiation to cancerous tissue.
The development of exquisitely precise beams has given birth to radiosurgery, the ability to destroy diseased tissues using radiation with surgical precision-but without the invasiveness of the scalpel. In its most common form, radiosurgery is used to treat tumors of the brain; of course, neurosurgeons are around for assistance. Many have heard about the gamma knife, a device frequently used to treat tumors of the brain and the pituitary gland. Traditional linear accelerators (the standard treatment machines in radiation oncology) can also be programmed to perform radiosurgery. What else lies on the horizon for this field? More radiosurgical gadgets are the on the way, including a cyber knife (with which radiosurgery will be possible nearly anywhere in the body) and tomotherapy (which uses a modified CT scanner to check patient position and correct daily variation moments before treating with a fanned beam of radiation).
Radiation oncologists are also experts of brachytherapy, the temporary or permanent placement of radioactive seeds and ribbons (depending on the organ) directly into the tumor itself. Because brachytherapy delivers radiation for a short distance before falling off to negligible amounts in surrounding tissue, oncologists find this method very appealing for primary or adjuvant radiation treatment. It can potentially wipe out the tumor without harming the neighboring tissue. Brachytherapy is often performed in the operating room and involves an interdisciplinary team-such as gynecologic oncologists, orthopedic surgeons, neurosurgeons, or urologists-who assist the radiation oncologist in performing the procedure.
THE DOCTOR-PATIENT RELATIONSHIP
Radiation oncologists do not spend all their time in the laboratory or conducting research trials. They typically see their patients for a short visit once a week during treatment. This appointment gives you the opportunity to address the patient's problems or acute side effects from radiation therapy. Once radiation treatment has ended, follow-up appointments continue, depending on the nature of the malignancy. These follow-up visits are extremely rewarding-particularly when a patient is cured. You are important to your patients, who are keen to recount the many happy events that have occurred in their lives since their last appointment.
Of course, not all of your patients will be cured. Radiation oncology has an important role in the palliation of patients with incurable disease. Although radiation treatment is used with the intent to cure, many malignant diseases have an extremely poor prognosis. If you enter this specialty, be prepared to cope with the emotional toll of caring for patients with cancer.
As an outpatient-based service, the practice of radiation oncology is calmer and less dramatic day to day than, for example, treating acutely ill patients on the general medicine wards. Nevertheless, a sizable percentage of your patients succumb to disease within a few years. Although emotionally draining at times, caring for these patients and their families is very rewarding. As you guide them through the rough seas of radiation therapy (not a pleasant treatment for anyone), patients want reassurance that they will not be abandoned. Remarkably, it is often this reassurance-more so than any promise of a miracle to cure-that provides patients and their families with solace, comfort, and peace of mind. One physician, for instance, makes an effort to convey to every patient that "I'll take you through hell and back to treat your cancer, but every single step of the way, I will always be there for you."
Like any physician, radiation oncologists are willing to accept the ambiguities of medicine and deal with issues that most people generally find frightening. Your patients' will to survive and endure intensive treatment-both radiation and chemical therapy-will humble and inspire you every single day. Indeed, this specialty can offer much perspective on life for any busy physician.
RADIATION ONCOLOGY AS A PALLIATIVE MODALITY
Through long-term relationships with their patients, radiation oncologists assess for clinical stability or signs of recurrence and manage any long-term sequelae of treatment. This is particularly important as these late effects can become manifest weeks to years down the line, and may even include iatrogenic (radiation-induced) secondary tumors. Your familiarity with radiation's true long-term effects on many organ systems will allow you to identify and medically intervene when necessary.
In light of the potential side effects from radiation treatment, if some patients cannot be cured, what role does this therapy have for them? You will find that radiation oncologists have an important role maintaining comfort for cancer patients by palliating local symptoms. Tumors of all types can be painful or even functionally obstructive. If surgery is no longer an option to resect the cancer, radiation becomes the preferred (or adjunctive) modality to shrink the tumor mass. In particular, radiation oncologists have much success in eliminating the severe pain caused by cancer (particularly lung, breast, or prostate) that has metastasized to bone. With just a couple of weeks of therapy, most patients report a partial or complete resolution of tumor-related bone pain.
The need for radiation therapy as a palliative measure to make patients feel better is often urgent. For instance, patients suffering from metastatic breast or prostate cancer may develop neurologic symptoms due to the tumor's extension from the vertebral body toward the spinal cord. In this case, radiation oncologists are called in for rapid treatment of spinal cord compression. They are the only specialists who can attempt to reverse quickly the neurologic deficit and prevent paralysis. They also help relieve the symptoms of superior vena cava syndrome, when tumors (usually lung cancer) grow and obstruct the main vessel draining blood from the head and neck into the heart.
BEING A PART OF MULTIDISCIPLINARY CANCER TREATMENT
Many medical students are under the misconception that chemotherapy will supplant radiation therapy. Although this is certainly not true, it is important to realize that radiation is just one of three major arms in the fight against cancer.
Long before radiation oncology, the only physicians who could treat cancer were the surgeons, who sought to prolong life by cutting out the tumor mass. Along came radiation therapy, a new modality that also helped to destroy cancerous tissue. Today, chemotherapy is often seen as the most promising therapy, especially because the general public has particularly high hopes that scientists and doctors will discover a magic pill to cure cancer completely.
Unfortunately, despite the technologic developments and other promises of twenty-first century medicine, a miracle cure is unlikely in the near future. Given our greater understanding of the mechanisms of cancer, no single modality - whether surgical, radiation, or chemical-will wipe out malignant disease. All future oncologists must accept the mantra that "different cancers in different stages respond to different schemes of therapy." This is why radiation oncologists are integral members of interdisciplinary cancer care teams whose members - across multiple specialties - work together to treat a patient afflicted with cancer.
Through conferences known as Tumor Board, the three major types of oncologists come together-along with pathologists and radiologists-to decide on the best course of treatment. Chemotherapy is particularly helpful for its systemic properties, dealing with small numbers of tumor cells that may spread throughout the body. Radiation, on the other hand, is especially valuable in treating the primary disease site, whether a gross tumor or microscopic disease. Frequently, radiation is superior to chemotherapy in treating bulky disease. Interestingly, chemotherapy can also act concomitantly with radiation as a sensitizer, thus enhancing the effects of radiation.
For the radiation oncologist then, an awareness of the multidisciplinary approach to cancer is essential. Although surgical oncologists can often resect all gross tumors seen with the naked eye, this approach may not be adequate to achieve a cure. Some cancers are particularly sensitive to radiation (like prostate cancer), whereas others respond quite well to chemotherapy (like the type of leukemia often found in kids). Radiation therapy might be used as the primary treatment (instead of surgery) or as a supplement to surgical or chemical therapy., This is especially important because often the appropriate dosage and the timing of radiation treatment depend upon whether or not the patient will go for surgery or certain types of toxic chemotherapy.
RADIATION ONCOLOGY EMPLOYMENT DATA
Median compensation: $303,750
Distribution among all physicians: 0.5%
Practice type: 78% in private practice; 22% in academics
Median patient care hours per week: 54.7
30% experienced difficulty in securing their preferred employment position
62% report that their salary is equal or higher than expected
Source: American Medical Association
LIFESTYLE CONSIDERATIONS AND PRACTICE OPTIONS
The lifestyle of a radiation oncologist is relatively benign compared to that of other specialists (although this may vary depending on the type of practice position). As hospital-based physicians practicing in an outpatient setting, they work predictable and humane hours, earn relatively generous salaries, and have low malpractice premiums. Although there are few oncologic-related emergencies that require immediate radiation treatment, most oncologists still carry a beeper, typically taking call from home for 1 week several times per year. As a result, there is ample time (including most weekends off) for radiation oncologists to spend with their families and pursue other interests.
Much of this "free time," however, is spent in research, scholarly pursuits, and keeping up with the latest medical literature. Radiation oncologists who are faculty members at an academic medical center have teaching and research responsibilities in addition to patient care. All doctors are life-long learners, and radiation oncologists, who have to learn about emerging technology all the time, perhaps best epitomize the importance of a significant amount of academic reading and studying.
After successfully passing the brutal board examinations (written and oral), newly certified radiation oncologists can decide among the three standard choices of practice: salaried academic jobs, community/private practice positions, or freestanding/private practice centers. As a primarily hospital-based specialty, the practice of radiation oncology requires an extensive amount of expensive equipment, supplies, and staff-all of which are usually covered by the hospital. In a recent career survey of new physicians, most board-eligible radiation oncologists (50%) favor private practice; 30% chose an academic setting. The remainder opted for fellowships, locum tenens, military work, or remained undecided.' Regardless of choice, the job market for young radiation oncologists coming out of residency is extremely good. In studies evaluating the trends in the job market for radiation oncologists, program directors viewed the job market strongly. Starting salaries are high and rising, and choice academic positions are available.
RADIATION ONCOLOGY 2002 MATCH STATISTICS
188 applicants competed for 97 positions
140 US seniors and 48 independent applicants ranked at least one radiation oncology program
Program directors ranked 11.2 candidates for each available position
97.9% of all positions were filled in the initial Match
The successful applicants: 89.6% US seniors, 7.2% foreign-trained physicians, and 3.2% osteopathic graduates
Unmatched rate for US seniors applying only to radiation oncology: 17.9%
RESIDENCY TRAINING
Residency in radiation oncology requires a total of 5 years of postgraduate training. There are currently 78 accredited programs in the United States, The first year (PGY-1) consists of a separate internship-preliminary medicine, surgery, or transitional year. Radiation oncology is an outpatient-based specialty, so most residents work about 60 hours per week with most weekends off except during call periods. On-call requirements typically last for 1 week at a time, during which the resident takes call from home and only comes to the hospital for an emergency. Despite the relatively benign work hours, residency training in radiation oncology is academically intense. Assignments, case presentations, and participation at conferences are required and frequent. A great deal of outside reading-particularly using the scientific literature-is necessary. To earn board certification after residency, you must pass three components of a written examination (clinical, radiobiology, and physics) as well as an oral examination.
Source: National Resident Matching Program
