Breast cancer was the first major malignancy demonstrated to be adequately treated with organ preservation. The impact of the randomized trials performed in the United States and Europe to investigate the effectiveness of radiation in securing local control in patients who had undergone lumpectomy for early-stage breast cancer cannot be underestimated. Not only has this influenced the treatment of this very prevalent disease, it has also motivated investigators of malignancies of other sites to explore the now popular concept of organ preservation.

Moderate doses of radiation are extremely effective at controlling subclinical populations of cancer cells. Over the past two decades, a better understanding of the nuances of breast cancer histology that impact on local control and refinements in radiation-therapy techniques have maximized the likelihood of control with minimal consequences to normal tissue.

This parallels the refinement of surgical and pathologic techniques that are a necessary component of the procurement and analysis of the tumor to guide further therapy.

Further refinements in surgical technique, such as sentinel lymph node biopsy, are gaining in popularity and will further challenge practicing oncologists to refine their treatment approaches in order to deliver the greatest likelihood of tumor control with the least likelihood of morbidity.

Among all malignancies, breast cancer investigations stand as a paradigm of multimodality collaboration to advance knowledge and patient care.

Radiation therapy is offered to breast cancer patients to rid the body of any microscopic cancer cells that may remain near the area where the cancer was originally found. The usual course of therapy includes daily treatments five days a week for five to seven weeks. Each session generally lasts an hour or less.

Radiation therapy is a process that precisely sends high levels of radiation directly to the cancer cells. Radiation done after surgery can kill cancer cells that may not be seen during surgery. Radiation may also be done:

 
• prior to surgery to shrink the tumor.  
• in combination with chemotherapy.  
• as a palliative treatment (therapy that relieves symptoms, such as pain, but does not alter the course of the disease).

There are various ways to deliver radiation therapy. However, external radiation is the usual type that is used for treatment of breast cancer. Consider the following:

 
• external radiation (external beam therapy) - a treatment that precisely sends high levels of radiation directly to the cancer cells. The machine is controlled by the radiation therapist. Since radiation is used to kill cancer cells and to shrink tumors, special shields may be used to protect the tissue surrounding the treatment area. Radiation treatments are painless and usually last a few minutes.  
• internal radiation (brachytherapy, implant radiation) - radiation is given inside the body as close to the cancer as possible. Substances that produce radiation, called radioisotopes, may be implanted directly into the breast tumor, or injected through a tube placed near the tumor.  Internal radiation involves giving a higher dose of radiation in a shorter time span than with external radiation. Internal radiation for breast cancer is currently being studied and is considered experimental.

A radiation oncologist will plan your radiation treatment based on your medical history, a physical examination, pathology and laboratory reports, and previous mammograms and surgeries. Your chest area will be marked with ink that must stay on your skin for the course of your treatments. These markings assure that the radiation will be given to the exact area requiring treatment.

Radiation therapy works by causing changes at the molecular level in tissues where the radiation beam is targeted. Giving all the radiation needed at one time would cause significant and irreparable damage not only to cancer cells, but also to normal cells. However, giving small doses of radiation each day enables the majority of healthy cells to repair any damage, while rendering cancer cells inactive.

Side Effects
The good news is that, apart from some general fatigue, there are few side effects associated with radiation therapy. Some women may develop one or more short-term side effects including a sunburn-like reaction on the areas of their skin that were irradiated, muscle stiffness, mild swelling, and tenderness. Others may have no perceptible side effects. Long-term side effects may include shrinking of the irradiated breast. There is no increased risk of cancer associated with radiation therapy, with the exception of an increased risk of lung cancer in heavy smokers.

Improving Cosmetic Outcome
Radiation oncologists at Memorial Sloan-Kettering have been studying the effects of radiation therapy on the breast in hopes of improving cosmetic outcome. For example, they have developed a special platform for overweight women with large breasts. The platform allows women to receive radiation therapy while lying on their stomachs. (Conventional radiation therapy to the breast is given to a patient lying on her back.) The treated breast suspends through an opening in the table below the patient, allowing radiation oncologists to target treatment better and to avoid radiating the tissue surrounding the breast.

IMRT
Our physicians are developing new radiation techniques, including intensity modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy. These techniques allow doctors to change the shape and intensity of radiation beams so they are focused more effectively on cancer cells, and away from the surrounding tissue and organs, thereby reducing toxicity. IMRT and three-dimensional conformal radiation therapy already are effective treatments for prostate cancer and are proving to be useful in treating breast cancer, as well.

Treatment for Recurrent Breast Cancer
Memorial Sloan-Kettering is also one of the few cancer centers where patients with recurrent breast cancer can be treated with radiation therapy even if radiation was used in the initial treatment of their cancer. Because the risk of side effects is greater when radiation therapy is used a second time, our physicians can help minimize those effects while maximizing the patient’s chances of successful treatment.

Our researchers are also participating in a new study that looks at whether or not women with certain types of ductal carcinoma in situ (DCIS), an early, preinvasive form of breast cancer, need radiation therapy in addition to breast-conserving surgery, or if surgery alone is enough. (Because of enhanced use of mammography, more women are being diagnosed with DCIS. Twenty to 25 percent of all the new breast cancers at Memorial Sloan-Kettering are DCIS.) Patients in this study will also have the option of receiving tamoxifen.

Karen D. Schupak
American College of Physicians