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AMAROS asked whether radiotherapy could replace surgery in an armpit known to contain cancer. It can: the cancer came back in the armpit in about one woman in a hundred either way, but arm swelling was half as common after radiotherapy.
AMAROS screened 4,806 patients with clinical T1 or T2 node-negative breast cancer by sentinel node biopsy and randomised the 1,425 who proved node-positive to axillary clearance (744) or axillary radiotherapy (681). The pre-planned ten-year analysis reported in 2023.
By intention to treat, the ten-year cumulative incidence of axillary recurrence was 0.93 percent after clearance (seven events) and 1.82 percent after radiotherapy (eleven events), a hazard ratio of 1.71 (95 percent confidence interval 0.67 to 4.39): both figures are very low, and the confidence interval is wide because the events are so few. There was no difference in overall survival (hazard ratio 1.17, 0.89 to 1.52) or disease-free survival (1.19, 0.97 to 1.46).
The reason to prefer radiotherapy is the arm. In the updated five-year analysis, lymphoedema occurred in 24.5 percent after clearance and 11.9 percent after radiotherapy (p<0.001), while quality-of-life scales did not differ. One finding cuts the other way and is reported as exploratory: the ten-year cumulative incidence of second primary cancers was 12.1 percent after radiotherapy and 8.3 percent after clearance.
The trial's own conclusion is that axillary radiotherapy is preferred over clearance for a patient with a positive sentinel node and T1 or T2 disease. In England, NICE NG101 recommendation 1.4.12 offers either.
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
1,425 randomised.
eleven events, 95 percent confidence interval 0.74 to 2.94 · seven events, 95 percent confidence interval 0.18 to 1.68
Source| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Cumulative incidence of axillary recurrence at 10 yearsprimary | Axillary radiotherapy | 681 | 1.82% | 1.71 (0.67 to 4.39) | - | link |
| Axillary lymph node dissection | 744 | 0.93% | ||||
| Lymphoedema at 5 years | Axillary radiotherapy | 681 | 11.9% | - | <0.001 | link |
| Axillary lymph node dissection | 744 | 24.5% | ||||
| Second primary cancers at 10 years (exploratory) | Axillary radiotherapy | 681 | 12.1% | - | - | link |
| Axillary lymph node dissection | 744 | 8.3% |
Shares SENOMAC, ACOSOG Z0011 (Alliance), Lymphoedema after breast cancer treatment, Doing less to the armpit.
Shares Lymphoedema after breast cancer treatment, Doing less to the armpit, Sentinel node biopsy, Lymphadenectomy (lymph node dissection).
Shares ACOSOG Z0011 (Alliance), Lymphoedema after breast cancer treatment, Doing less to the armpit, Sentinel node biopsy.
Shares Lymphoedema after breast cancer treatment, Doing less to the armpit, Sentinel node biopsy, Sentinel lymph node biopsy.
Shares POSNOC, Lymphoedema after breast cancer treatment, Doing less to the armpit, Sentinel node biopsy.
Shares Lymphoedema after breast cancer treatment, Doing less to the armpit, Sentinel node biopsy, Sentinel lymph node biopsy.
Shares Doing less to the armpit, Sentinel node biopsy, Lymphadenectomy (lymph node dissection), Sentinel lymph node biopsy.
Shares ACOSOG Z0011 (Alliance), Doing less to the armpit, Lymphadenectomy (lymph node dissection), HER2-positive breast cancer.