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Radiotherapy after breast-conserving surgery halves the chance of the cancer coming back and prevents about one death in breast cancer for every four recurrences it prevents. In older women with small, hormone-sensitive, slow-growing tumours who will take endocrine therapy, the recurrence risk is so low to start with that leaving radiotherapy out changes almost nothing.
The size of the benefit was measured once and definitively. The Early Breast Cancer Trialists' Collaborative Group pooled individual data for 10,801 women in 17 randomised trials of radiotherapy against none after breast-conserving surgery. Radiotherapy cut the ten-year risk of any first recurrence from 35.0 to 19.3 percent (absolute reduction 15.7 percent) and the fifteen-year risk of death from breast cancer from 25.2 to 21.4 percent (absolute reduction 3.8 percent). The relationship that lets the benefit be predicted is the one the overview named: about one breast cancer death is avoided by year fifteen for every four recurrences avoided by year ten. The proportional benefit varies little between groups of women; the absolute benefit varies a great deal, and can be predicted before treatment from age, grade, oestrogen receptor status, tamoxifen use and the extent of surgery.
Three trials found the group in whom the absolute benefit is small enough to discuss omitting. CALGB 9343 randomised 636 women aged 70 or over with stage I oestrogen receptor-positive disease on tamoxifen and found ten-year locoregional recurrence of 10 percent without radiotherapy against 2 percent with it, and no difference in mastectomy rates, distant disease or survival. PRIME II randomised 1,326 women aged 65 or over with node-negative hormone receptor-positive tumours up to 3 cm and found ten-year local recurrence of 9.5 against 0.9 percent with no difference in survival. LUMINA took 500 women aged 55 or over with grade 1 or 2 T1N0 luminal A disease, selected by biology rather than age alone, and found five-year local recurrence of 2.3 percent without radiotherapy.
In England the rule is written down. NICE NG101 recommendation 1.13.7 considers not using radiotherapy for women aged 65 and over with clear margins and a very low absolute risk of local recurrence, defined as T1N0, oestrogen receptor-positive, HER2-negative, grade 1 to 2, who are willing to take endocrine therapy for at least five years. Recommendation 1.13.8 says what has to be explained: without radiotherapy, local recurrence occurs in about 50 women per 1,000 at five years, and with it in about 10 per 1,000; overall survival at ten years is the same either way; and in this low-risk group there is no increase in serious late effects such as heart failure, heart attack or second cancer from having radiotherapy.
The corollary is the one that gets lost. Omission is an option for a narrow group, defined by age, size, grade, receptor status and a commitment to endocrine therapy. Outside that group radiotherapy after breast conservation is standard, and NICE NG101 recommendation 1.13.3 offers it to every woman with invasive cancer and clear margins.
Showing the technology this term belongs to: IMRT / IGRT (modern external beam).
Shares Tumour bed boost, NSABP B-06, Lumpectomy (breast-conserving surgery), HER2-positive breast cancer.
Shares Radiotherapy after mastectomy, Partial-breast irradiation, Hypofractionation (fewer, larger radiotherapy doses), HER2-positive breast cancer.
Shares Tumour bed boost, Lumpectomy (breast-conserving surgery), HER2-positive breast cancer, Breast cancer (all types).
Shares Partial-breast irradiation, Hypofractionation (fewer, larger radiotherapy doses), HER2-positive breast cancer, Breast cancer (all types).
Shares Tumour bed boost, Partial-breast irradiation, HER2-positive breast cancer, Breast cancer (all types).
Shares Partial-breast irradiation, Hypofractionation (fewer, larger radiotherapy doses), HER2-positive breast cancer, Breast cancer (all types).
Shares Partial-breast irradiation, Lumpectomy (breast-conserving surgery), HER2-positive breast cancer, Breast cancer (all types).
Shares NSABP B-06, Lumpectomy (breast-conserving surgery), HER2-positive breast cancer, Breast cancer (all types).