Omission of radiation therapy for favorable, early-stage breast cancer

CALGB 9343 was a phase III randomized trial of radiation omission. A total of 636 women were enrolled; 317 women received tamoxifen plus radiation therapy, and 319 women received tamoxifen alone. Eligible women were aged 70 years or older and had clinical stage I estrogen receptor (ER)-positive breast cancer. Initial eligibility criteria included breast cancers measuring up to 4 cm regardless of ER status, but in August 1996 this was reduced to measuring up to 2 cm (T1) with ER-positive or indeterminate receptor status. Patients were required to have clinically negative axillae.[12][Level of evidence A1]

CALGB 9343 was a phase III randomized trial of radiation omission. A total of 636 women were enrolled; 317 women received tamoxifen plus radiation therapy, and 319 women received tamoxifen alone. Eligible women were aged 70 years or older and had clinical stage I estrogen receptor (ER)-positive breast cancer. Initial eligibility criteria included breast cancers measuring up to 4 cm regardless of ER status, but in August 1996 this was reduced to measuring up to 2 cm (T1) with ER-positive or indeterminate receptor status. Patients were required to have clinically negative axillae.[12][Level of evidence A1]

At 10 years, 98% of patients in the tamoxifen-plus-radiation group (95% CI, 96%–99%) were free from local and regional recurrences compared with 90% in the tamoxifen-alone group (95% CI, 85%–93%).

CALGB 9343 was a phase III randomized trial of radiation omission. A total of 636 women were enrolled; 317 women received tamoxifen plus radiation therapy, and 319 women received tamoxifen alone. Eligible women were aged 70 years or older and had clinical stage I estrogen receptor (ER)-positive breast cancer. Initial eligibility criteria included breast cancers measuring up to 4 cm regardless of ER status, but in August 1996 this was reduced to measuring up to 2 cm (T1) with ER-positive or indeterminate receptor status. Patients were required to have clinically negative axillae.[12][Level of evidence A1]

There were no significant differences in time-to-mastectomy, time-to-distant metastasis, breast cancer–specific survival, or survival between the two groups. The 10-year overall survival (OS) rate was 67% (95% CI, 62%–72%) in the tamoxifen-plus-radiation group, and 66% (95% CI, 61%–71%) in the tamoxifen-alone group.

PRIME-II was a phase III trial of radiation omission. A total of 1,326 women were randomly assigned to receive either whole-breast irradiation (n = 658) or no irradiation (n = 668). Eligible women were aged 65 years or older and had hormone receptor–positive, node-negative, T1 or T2 primary breast cancer (with tumors measuring ≤3 cm in the largest dimension). Patients had previously undergone breast-conserving surgery with clear excision margins and adjuvant endocrine therapy.[13][Level of evidence A1]

PRIME-II was a phase III trial of radiation omission. A total of 1,326 women were randomly assigned to receive either whole-breast irradiation (n = 658) or no irradiation (n = 668). Eligible women were aged 65 years or older and had hormone receptor–positive, node-negative, T1 or T2 primary breast cancer (with tumors measuring ≤3 cm in the largest dimension). Patients had previously undergone breast-conserving surgery with clear excision margins and adjuvant endocrine therapy.[13][Level of evidence A1]

At a median follow-up of 10 years, the cumulative incidence of local breast cancer recurrence was 9.5% (95% CI, 6.8%–12.3%) in the no-radiation therapy group and 0.9% (95% CI, 0.1%–1.7%) in the radiation therapy group. The 10-year OS rate was almost identical in the two groups, at 80.8% (95% CI, 77.2%–84.3%) in the no-radiation therapy group and 80.7% (95% CI, 76.9%–84.3%) in the radiation therapy group.