Multiple Various Therapies Effective for Overall Breast Cancer Survival

December 18, 2006

SAN ANTONIO -- Breast cancer clinicians seem to be on the right track with their use of radiotherapy, chemotherapy regimens, and tamoxifen, showing a major mortality decline, according to a meta-analysis of clinical trial evidence.

SAN ANTONIO, Dec. 18 -- Breast cancer clinicians seem to be on the right track with their use of radiotherapy, chemotherapy regimens, and tamoxifen, showing a major mortality decline, according to a meta-analysis of clinical trial evidence.

The five-year update by the Early Breast Cancer Trialists' Collaborative Group (EBCTCG), presented at the San Antonio Breast Cancer Symposium here by epidemiologist Richard Peto, Ph.D., of the University of Oxford in England, held no surprises but confirmed that radiotherapy, chemotherapy combinations, and tamoxifen were steadily reducing disease mortality.

Overall, said Dr. Peto, breast cancer mortality rates have been dropping worldwide since the late 1980s, likely because of effective treatments, early diagnosis by mammography, better adjuvant treatment, and better treatment for relapse.

Each individual treatment has had only a moderate effect but they appear to have been additive, Dr. Peto said.

"These are all small differences but overall breast cancer death rates by 2010 in middle age will be down to half or less than half of what they were in 1990," he said. "That is because of better management; it's not because of breakthroughs. It's because a small gain from this and then a further small gain from something else and a further a small gain from something else."

Yet the presentation here was missing anticipated first-time overall evaluations of taxane chemotherapy, the aromatase inhibitors, tamoxifen therapy duration, and ovarian ablation or suppression.

Unfortunately some of the major trials in these areas did not provide their data soon enough to be included in the meta-analysis, Dr. Peto said.

"I was disappointed there was not more data to release," added Peter M. Ravdin, M.D., Ph.D., of the M.D. Anderson Cancer Center in Houston, who is a member of the group's steering committee.

Dr. Ravdin hinted that next year's presentation is likely to find aromatase inhibitors superior to other hormonal therapies. The anticipation is that adding the positive trials already reported with the yet-unpublished data may even uncover a survival advantage that has narrowly evaded researchers in the individual trials, he said.

The collaborative group releases a meta-analysis every five years with the goal of including the data from every woman in every randomized clinical trial in the field. For the 2005 to 2006 meta-analysis, the researchers had data on 823 trials with 661,000 patients.

For radiotherapy the researchers found:

  • Among women who underwent mastectomy, radiotherapy reduced local recurrence rates over five years by 2.8% for those with no positive lymph nodes, 15.7% for one to three positive nodes, and 22.3% for four or more lymph nodes.
  • Among women who underwent mastectomy, radiotherapy reduced breast cancer mortality over 15 years for women with one to three or four or more positive lymph nodes (7.6% and 6.9% gain, respectively) but not for node negative women (0.6%, P=not significant).
  • For women who underwent breast conservation surgery with node negative or positive disease, the gains were significant for isolated local recurrence (14.4% and 25.1% over five years, respectively), breast cancer mortality (3.1% and 7.8% over 15 years, respectively), and overall mortality (3.8% over 15 years).
  • Overall non-breast-cancer mortality was worse with radiotherapy over the more than 20 years of follow up (treatment effect 1.16, P