“Optimal” radiation therapy best bet for surviving breast cancer

Although radiation therapy following a mastectomy is known to reduce the risk of breast cancer recurring, the effect of radiation therapy on survival has long been controversial.

There has always been concern regarding the long term health effects of radiation therapy, in particular regarding the heart.

A new study has found that for breast cancer patients who have undergone a mastectomy, radiation therapy improves survival but only when the dose is appropriate and the target area is sufficient.

At present the accepted approach to radiation therapy is thought to minimize the exposure to the heart, and it is expected that the currently accepted doses and broad target areas will show survival benefits.

It has been suggested that previous studies which failed to find a survival benefit of radiation therapy did not take into account the quality of the radiation therapy provided.

In order to assess the relationship between post-mastectomy radiation therapy and survival, the researchers conducted an analysis of 38 clinical trials.

All of the studies enrolled women with operable breast cancer that was first treated by mastectomy, and each study compared radiation therapy to no radiation therapy. The studies involved a total of 13,199 women.

The quality of radiation therapy administered in each trial was classified into 3 categories:

• Optimal radiation therapy, where the radiation dose was 40-60 Gy in 2-Gy fractions administered to the chest wall, the axillary lymph nodes, and the area right above the collarbone.

• Category 2: Inadequate or excessive radiation therapy, where the dose was below 40 Gy or above 60 Gy.

• Category 3: Incomplete tissue coverage, where the radiation was administered to an area smaller than the chest wall and regional lymph nodes.

In the category 1 studies radiation therapy improved survival by 6.4%.over 10 years.

In the category 2 and category 3 studies radiation therapy did not significantly improve 10-year survival.

The risk of the cancer recurring was also evaluated and it was found that radiation therapy reduced the risk of recurrence to a greater extent in category 1 studies than in category 2 or category 3 studies.

The researchers concluded that radiation therapy given in an appropriate dose to an adequately large area of the body improves survival for up to 10 years.

The results are published in the Journal of the National Cancer Institute.