Radiation Treatment Side Effects

The rate of lymphedema in patients who have had limited axillary dissections is reported to be approximately 5%. Due to the fact that radiation fields need to encompass the axillary tail of breast tissue, a small portion of the axillary contents are usually irradiated, and this will result in a small increase in the rate of lymphedema to approximately 7%.

An important component of the long-term follow-up for patients who have undergone breast-conservation surgery utilizing radiation is evaluation for early evidence of lymphedema. When dealt with promptly, while at a subtle stage, this condition can almost always be controlled and, frequently, reversed entirely.

If, however, the condition is permitted to advance to a rather dramatic stage, the prospects for complete reversal diminish. The contribution that a patient may make to the avoidance of lymphedema and to its early and aggressive management, should it occur, cannot be underestimated. Our patients are instructed to limit weight bearing to a maximum of 5 lbs on the operated side, and there can be no blood drawing, no IV placement or blood-pressure readings taken on the effected side.

Patients are instructed not to hang their handbags over the shoulder on the effected side. Any insect bite or minor cuts or scrapes should be treated promptly with antibiotic ointment, and if the area becomes inflamed, oral antibiotics should be administered without delay. Lymphedema is a lifelong risk and may develop many years after surgery.

In its most extreme form, chronic and profound lymphedema after radiation can lead to Stewart-Treves syndrome, where lymphosarcoma, a rapidly fatal soft-tissue malignancy, may occur.

The most dreaded long-term consequence of radiation therapy is the possible induction of a second malignancy. This has been carefully studied and reviewed by many centers.

The possibility of inducing a primary tumor in the bone or soft tissue of the chest wall is estimated at 1 in 500 to 1 in 1,000. The latency for such tumors is generally between 7 and 14 years time, further highlighting the importance of lifelong follow-up for patients who have undergone treatment for an early-stage breast cancer.

Even the most meticulously planned and delivered radiation treatments will deliver a small “scatter” dose to the contralateral breast. This has been measured and quantified and, theoretically, should increase the risk of contralateral breast cancer slightly. In fact, this correlation has not been generally found, although there are several studies that suggest that women younger than 40 who have been irradiated for their index tumor have a higher incidence of contralateral breast cancer than those who have undergone mastectomy for their index tumor.  In this setting, we omit the medial wedge if at all possible to further decrease the scatter dose of radiation. It is not clear whether such women, who develop their index cancer prior to age 40, have a genetic predisposition to favor initiation of a second tumor with small doses of radiation.

Karen D. Schupak
American College of Physicians


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