EBCTCG previous findings
- Report on 37,000 women in 26 trials of chemotherapy dose intensification showed that increasing dose intensity (eg by 2-weekly rather than 3-weekly administration) reduced the risk of breast cancer recurrence and death.
- Report on 4500 women in 10 trials of neoadjuvant chemotherapy (given before surgery) versus adjuvant chemotherapy (given after surgery) showed that there was no significant different between neoadjuvant and adjuvant chemotherapy for distant recurrence, breast cancer mortality or death from any cause. Neoadjuvant chemotherapy allowed more women to have breast-conserving therapy than adjuvant chemotherapy. However, the risk of cancer recurring in the breast or adjacent lymph glands (local recurrence) was somewhat higher in the neoadjuvant than the adjuvant chemotherapy group. This increased risk of local recurrence was greater in trials which omitted surgery in the event of a good response to neoadjuvant chemotherapy.
- Report on the 20-year risks of breast cancer recurrence after stopping endocrine therapy after 5 years showed that when endocrine therapy ended, the risk of the cancer reappearing and spreading throughout the body continued at a similar rate over at least the next 15 years. The risk depended mainly on the original cancer’s size, and the number of lymph nodes that were cancerous. But, even for those patients with the best outlook (small tumours with no spread to the lymph nodes), there was a 10% chance of cancer spread 20 years after the initial diagnosis, sufficient for further endocrine therapy to be at least considered
- Report on the risks of breast cancer radiotherapy included more than 40,000 women in 75 randomised trials and showed that that late side-effects of modern radiation therapy for breast cancer depend largely on a woman’s smoking status. For non-smokers, the absolute risks of lung cancer and heart disease from modern radiation therapy were <1%. But for long-term continuing smokers they were close to 5%, which may outweigh the benefit. Stopping smoking at the time of radiotherapy may avoid much of this risk.
- Report on 20 000 women in 26 randomised trials of bisphosphonates, showed that 2–5 years of treatment with these drugs, which are usually used to treat osteoporosis, reduces the risk of breast cancer recurring in the bones, and significantly extends survival. However, bisphosphonate treatment appears effective only for post-menopausal women and had little effect in premenopausal women.
- Report on 30 000 postmenopausal women in 9 randomised trials comparing aromatase inhibitors (AIs) with tamoxifen, showed that 5 years of treatment with an AI produces even better survival than five years of tamoxifen. Compared to tamoxifen, taking AIs for five years further reduced the likelihood of the cancer recurring by 30%, and the risk of dying from breast cancer by around 15%. Thus taking an AI for 5 years, compared to no endocrine treatment, would reduce the risk of dying from breast cancer by around 40% in the decade after starting treatment.
- Lancet report showed that after mastectomy and axillary clearance radiotherapy reduced breast cancer recurrence and mortality not only in women whose breast cancer had spread to many lymph nodes but also in those with spread to only 1-3 axillary lymph nodes.
- Report on 20 000 women in 20 randomised trials of about 5 years of tamoxifen versus no tamoxifen, showed a highly significant reduction of about a third in breast cancer mortality not only during years 0-4 and 5-9 after starting treatment but also during years 10-14. Tamoxifen is effective whether or not chemotherapy has been given and, importantly, even in weakly ER positive disease.
- 2011/12 Lancet reports updated evidence from 2005, bringing together data from 100,000 women in 123 randomised trials of chemotherapy, showing that chemotherapy can reduce breast cancer mortality not only in ER-negative but also in ER-positive disease, and showing benefits of taxane-based over standard anthracycline chemotherapy.
- Report on radiotherapy after breast-conserving surgery showed that radiotherapy halves the rate at which the disease recurs and reduces the breast cancer death rate by about a sixth.
- Report on surgery and radiotherapy showed that regimens that substantially reduce 5-year local recurrence rates have little effect on 5-year breast cancer mortality, but moderately reduce 15-year breast cancer mortality.
- Lancet report on systemic therapies showed the substantial effects on 15-year survival of the chemotherapy regimens (eg, about 6 months of anthracycline-based chemotherapy) and endocrine regimens (eg, 5 years of tamoxifen) that were being tested in the 1980s.