Related Pages Search for Clinical Trials 1 NCI's PDQ® Cancer Clinical Trials Registry. Breast Cancer Home Page 2 NCI's gateway for information about breast cancer. Postmastectomy Radiation Therapy and Survival 3 Radiation therapy after mastectomy for breast cancer increases both five-year and 10-year survival for women at high risk of recurrence, as long as doctors use appropriate radiation therapy, according to the Jan. 4, 2006, issue of the Journal of the National Cancer Institute.

Key Words

Breast cancer, radiation therapy. (Definitions of many terms related to cancer can be found in the Cancer.gov Dictionary ⁴.)

Summary

Combined data from 78 randomized clinical trials show that radiation therapy after either breast-conserving surgery (BCS) or mastectomy in women with early breast cancer significantly reduces both five-year recurrence and 15-year mortality rates. This is the first research to show that postsurgical radiation therapy in this group of patients helps them to live longer in addition to lowering their risk of local recurrence.

Source

The Lancet, Dec. 17, 2005 (see the journal abstract).
(Lancet. 2005 Dec 17;366(9503):2087-106)

Background

In women with early-stage breast cancer treated with surgery alone (breast-conserving surgery or mastectomy), microscopic residual disease may not be eliminated and can eventually cause life-threatening metastatic recurrence. Radiation therapy after surgery has been widely recommended for women at high risk of recurrence, based on the results of clinical trials showing that such treatment cuts the rate of local recurrence (a return of cancer in the remaining breast tissue, scar, chest wall, or nearby lymph nodes).

However, the same trials, taken individually, have failed to show whether these women actually lived longer thanks to the additional radiation therapy.

For that reason, even with widespread support, these recommendations are not always heeded. When detected early enough, local recurrence can often be treated with additional surgery alone, so some physicians and patients still elect to avoid radiation therapy and its associated side effects.

The Study

Combined data (called a meta-analysis) from 42,000 women - collected from 78 randomized trials begun between 1958 and 1991 - was performed by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG). The availability of extensive 15-year survival data allowed the investigators to reliably quantify the relationship between successful local control and long-term survivorship.

The individual trials compared varying types of local control:

• radiation therapy after breast-conserving surgery (BCS) vs. no radiation therapy after BCS
• postmastectomy radiation therapy vs. no postmastectomy radiation therapy
• more extensive surgery vs. less extensive surgery
• more extensive surgery versus less extensive surgery, with radiation therapy after both
• more extensive surgery vs. less extensive surgery, with radiation therapy only after less extensive surgery

The EBCTCG reviewed the trial results for how long it took breast cancer to recur; whether recurrence was local or distant; mortality (due to breast cancer or otherwise); and the incidence of second primary cancers before breast cancer recurrence.

Results

Radiation therapy after breast-conserving surgery was responsible for a highly statistically significant reduction in local recurrence. Combined, the data showed a 19 percent absolute reduction of the risk of recurrence five years after treatment. Although none of the trials showed a significant reduction in 15-year mortality when analyzed on their own, the meta-analysis revealed a highly significant absolute reduction of 5.4 percent.

For women with cancer that had spread to the lymph nodes (node-positive) and who underwent a full mastectomy, postoperative radiation therapy provided a similar reduction in recurrence and mortality: a 17 percent absolute reduction of the risk of recurrence five years after treatment and a 5.4 percent reduction in 15-year mortality.

When subgroups were analyzed, the investigators found that the higher the risk of recurrence, the greater the potential benefit of post-surgery radiation therapy. The investigators concluded that for any group of early breast cancer patients, a local treatment difference that reduces the five-year local recurrence risk by 20 percent would reduce the 15-year breast cancer mortality by 5.2 percent.

In other words, says Jeff Abrams, M.D., of the National Cancer Institute’s Cancer Therapy Evaluation Program, “for every four local recurrences that are avoided by the addition of radiation therapy, about one breast cancer death could be avoided over the next 15 years.”

Limitations

The one drawback of radiation therapy noted by the EBCTCG meta-analysis was an increase in the incidence of secondary cancers (new cancers unrelated to the original breast cancer) and in mortality from heart disease and lung cancer. However, the investigators emphasize that modern radiation therapy technology now minimizes the radiation doses to the heart, lungs, and other breast, compared to the doses given at the time these trials were conducted.

Comments

"These long awaited results from the EBCTCG overview analysis demonstrate an important effect for adjuvant radiation therapy in the treatment of primary breast cancer," says Abrams, noting that the survival benefit is apparent both in women who undergo breast-conserving surgery and those with cancer in their lymph nodes who undergo a mastectomy.

The authors place their results in the context of combination therapy, and state that “the moderate differences in 15-year breast cancer mortality produced by better local control can be combined with the moderate differences produced by chemotherapy and hormonal therapy…yielding in total quite substantial effects on 15-year breast cancer mortality.”

Glossary Terms

An operation to remove the breast cancer but not the breast itself. Types of breast-conserving surgery include lumpectomy (removal of the lump), quadrantectomy (removal of one quarter, or quadrant, of the breast), and segmental mastectomy (removal of the cancer as well as some of the breast tissue around the tumor and the lining over the chest muscles below the tumor). Also called breast-sparing surgery.

Surgery to remove the breast (or as much of the breast tissue as possible).

The spread of cancer from one part of the body to another. A tumor formed by cells that have spread is called a “metastatic tumor” or a “metastasis.” The metastatic tumor contains cells that are like those in the original (primary) tumor. The plural form of metastasis is metastases (meh-TAS-tuh-SEEZ).

A study in which the participants are assigned by chance to separate groups that compare different treatments; neither the researchers nor the participants can choose which group. Using chance to assign people to groups means that the groups will be similar and that the treatments they receive can be compared objectively. At the time of the trial, it is not known which treatment is best. It is the patient's choice to be in a randomized trial.

Describes a mathematical measure of difference between groups. The difference is said to be statistically significant if it is greater than what might be expected to happen by chance alone. Also called significant.