The increased success of breast cancer treatment owes a great deal to the effective use of radiation therapy. Patients often receive radiation following their surgery (mastectomy or lumpectomy) to destroy stray cancer cells in the breast and surrounding lymph node area. As a result, most early-stage breast cancer patients are now cured of their disease without the cancer returning.
Memorial Sloan Kettering has long been recognized as a pioneer in treating cancer with radiation. For example, beginning in the 1980s, our radiation oncologists and medical physicists played a leading role in developing intensity modulated radiation therapy (IMRT), which targets tumors with multiple beams at different angles and intensities to conform to the tumor shape. After refining this technique and then demonstrating its immense clinical value, our doctors have used IMRT as a standard breast cancer treatment for 15 years.
We continue to refine radiation therapy to make it even safer and more effective. Here are just a few ways that we have improved treatments for our breast cancer patients.
Less Is More: Hypofractionated Radiation
MSK was one of the first institutions to adopt hypofractionated radiation therapy, a form of radiation that’s more highly concentrated than standard radiation therapy and given over a shorter period of time, with higher doses in each session. Many breast cancer patients now receive hypofractionated therapy.
In addition to being more convenient for patients because it requires fewer visits, long-term studies show hypofractionated therapy also can be more effective. “The outcome — including the control rate and the cosmetic outcome, or lack of scar tissue — is better with the shorter course of radiation,” says MSK radiation oncologist Beryl McCormick. “So it’s a win-win situation for the patients.”
Doing the Heart Good
When the cancer is in the left breast, doctors need to take special precautions to prevent radiation from causing unnecessary damage to the heart. One way to do this is through prone breast radiation, in which the patient lies on her stomach and radiation is directed to the affected breast as it hangs through an opening in the treatment table. This approach is especially useful for older patients and women with large breasts, as gravity pulls the breast away from the heart.
Another heart-protecting technique recently adopted at MSK is called deep inspiration breath hold. Patients take a deep breath and hold it in so that the lungs push the heart away from the breast while the radiation is being delivered.
“We can measure a patient’s lung capacity, and our computerized program will shut off the radiation the instant they begin to stop holding their breath so that the beam does not hit the heart if it moves into the radiation field,” Dr. McCormick says.
Breast-Specific Radiation Expertise
In putting together a treatment plan for a breast cancer patient, radiation oncologists define the target as well as the nearby structures where radiation doses should be minimized. Medical physicists, working as part of the team, design the optimal plan using mathematical modeling and advanced computer programs.
The large number of patients treated at MSK allows our radiation oncologists and medical physicists to become very specialized. Since 2013, treatment planning at MSK has been site-oriented, meaning that the radiation oncologists and medical physicists are trained in designing treatments for one specific part of the body.
“We are one of just a few places that has a dedicated team focused only on treating breast cancer,” Dr. McCormick explains. “Because they are exclusively focused on breast treatment plans, we get some really creative, beautiful ways of delivering radiation.”
Another innovative approach involves spreading the radiation dose over a larger number of beams, making it possible to cover the treatment area more thoroughly without increasing risk for damage to the heart and lungs. This technique, while still being investigated, appears to be as safe as more conventional methods and may provide some unexpected cosmetic benefits.
Because the higher number of beams provides a more evenly spread dose, there are fewer pockets of high radiation that can cause red or dark spots in the breast skin. It also may minimize or prevent fibrosis — a scarring and stiffness in the breasts of women with implants. This benefit alone would be very important, as women have made it clear that these side effects are a major concern.
Some women can benefit from an advanced form of radiation therapy called proton therapy, which can be effective against tumors that may be resistant to other forms. While proton therapy kills cancer cells through a process similar to that used in x-ray radiation — by damaging their DNA — the unique physical properties of protons allow them to deliver the dose at a specific depth in the body. This cutting-edge technology is available at a limited number of locations in the United States.
The Next Wave
Perhaps the next big advance in breast cancer treatment involves radiomics — trying to understand why, given the same dose, patient A does better than patient B. Researchers are learning that different mutations may influence the radiosensitivity of a person’s cells. Certain breast cancers, for example, may be more sensitive to radiation than others because of mutations in the BRCA genes. On the other hand, if the breast cancer will not be radiosensitive, patients might be spared the inconvenience and side effects of an ineffective treatment.
“We have a deep commitment here to continually improving the delivery of radiation so it’s more personalized for every patient,” Dr. McCormick says. “Every step forward helps improve outcomes while minimizing the treatment burden.”