More Long Term Survival Clues

[Tom]

Prevention of local breast cancer recurrence reduces mortality 15 years later

Reuters Health
Posting Date: December 15, 2005

Last Updated: 2005-12-15 18:30:10 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Postsurgical radiotherapy for treatment of breast cancer reduces the rate of local recurrence during the next 5 years, results of a large study show, and for every four local recurrences prevented there is one less death due to breast cancer over the ensuing 15 years.

The Early Breast Cancer Trialists' Collaborative Group (EBCTCG) conducted meta-analyses of 78 randomized trials of local therapy that began by 1995, which involved 42,080 women and 24 different comparisons. They report their findings in December issue of The Lancet.

"About three-quarters of the local recurrence risk (and more than three-quarters of any treatment effects on local recurrence) occurred during the first 5 years after randomization," the investigators report. "By contrast, more than half of the 15-year breast cancer mortality (and much more than half of any such treatment effects on breast cancer mortality) occurred after the first 5 years."

They found that some local treatment comparisons had little effect (< 10%) on either recurrence or mortality, including axillary clearance versus effective axillary radiotherapy, mastectomy versus breast conserving surgery (BCS) plus effective radiotherapy, and post-mastectomy radiotherapy in node-negative disease.

However, the 10 trials of post-BCS radiotherapy showed significantly reduced local recurrence in each trial. Radiotherapy also reduced risk after mastectomy and axillary clearance, with more benefit for those with node-positive disease.

Results showed that the differences in breast cancer mortality are greater at 15 years than at 5 years, and are in proportion to the differences in 5-year local recurrence risk. Local treatment that decreased the 5-year local recurrence risk by 20% was found to reduce 15-year breast cancer mortality by 5.2%.

The authors note that earlier diagnosis and modern advances in surgery and systemic therapy have resulted in lower risk of recurrence. Nevertheless, the quantitative relationship between local disease and long-term breast cancer mortality will probably continue to apply.

In a press statement, study coordinator Professor Sir Richard Peto, from the University of Oxford in the UK, comments that these results may be relevant to patients who initially did not undergo radiation therapy.

"There would probably be little point in offering radiotherapy to women who have been free of cancer for the past few years," he notes. "But it might be worth considering radiotherapy for some women who, within just the last year or two, have had lumpectomy for breast cancer or mastectomy for cancer that had spread to the armpit, and who didn't get radiotherapy after surgery because of the side effects."

Lancet 2005;366:2087-2106.