Researchers confirm axillary node dissection unnecessary for all node-positive breast cancers

SAN ANTONIO — The 10-year follow-up results of the IBCSG 23-01 trial confirmed that complete axillary node dissection may not be required for all patients with node-positive breast cancer, including those undergoing mastectomy, according to results of the phase 3, multicenter, randomized, noninferiority trial presented at the San Antonio Breast Cancer Symposium.

“Axillary node dissection was once the standard approach to the axilla [among] patients with metastatic sentinel nodes,” Viviana Galimberti, MD, director of the unit of molecular senology at European Institute of Oncology and researcher with the International Breast Cancer Study Group, said during her presentation. “However, the 5-year results of IBCSG 23-01 and 10-year results of the Z0011 trial showed that, for patients with moderate axillary involvement, axillary node dissection provided no advantage in terms of DFS or OS, while axillary failure rates were low.”

The analysis included 931 women (median age, 54 years; 56% postmenopausal; 90% ER positive; 75% PR positive) with cancers of pathological diameter 5 cm or smaller and one or more micrometastatic foci 2 mm or smaller, including isolated tumor cells, in the sentinel nodes. Between April 2001 and February 2010, researchers randomly assigned patients to axillary node dissection (n = 464) or no axillary node dissection (n = 467).

Women underwent conservative breast surgery (91%) or mastectomy (9%). Those with axillary macrometastases were excluded from the study.

Invasive DFS served as the primary endpoint; secondary endpoints included OS, site of recurrence — particularly axillary recurrence — and surgical complications of axillary node dissection.

Median follow-up was 9.8 years.

The rate of 10-year DFS appeared similar among patients who did not and who did undergo axillary dissection (77% vs. 75%; HR = 0.85; 95% CI, 0.65-1.11), indicating noninferiority (P = .002).

There were 45 deaths in the no-axillary node dissection arm compared with 58 deaths in the axillary node dissection arm. Researchers reported 10-year OS rates of 91% in the no-dissection arm compared with 88% in the axillary node dissection arm (HR = 0.77; 95% CI, 0.56-1.07).

Moreover, the cumulative incidence of breast cancer events also appeared similar between the two arms (no dissection, 17.6% vs. dissection, 17.3%; HR = 0.96; 95% CI, 0.71-1.36).

Only 0.4% of women in the axillary node dissection arm and 1.7% in the no-dissection arm experienced ipsilateral axillary events.

When researchers analyzed total DFS events according to surgery type, they found non-breast cancer events occurred among 7.5% of patients who underwent breast conservation and 7% who underwent mastectomy. Additionally, death occurred among 16.3% of women who underwent mastectomy compared with 10.5% of those who underwent breast conservation.

“After the median follow-up of 9.8 years, we found no differences between the two arms for DFS or OS,” Galimberti said. “Our findings are fully consistent with those in the Z0011 trial, which after 10 years, found no differences between the axillary dissection or no-axillary dissection arms for any endpoint [among] patients with moderate disease burden in the axilla undergoing conservative breast surgery.”

“We also suggest that nonaxillary dissection is acceptable treatment [among] patients scheduled for mastectomy,” Galimberti added. “Our data fully support the change in clinical practice that started after the early published results, 5 years ago.” – by Jennifer Southall

Reference:

Galimberti V, et al. Abstract GS5-02. Presented at: San Antonio Breast Cancer Symposium; Dec. 5-9, 2017; San Antonio.

Disclosures: Galimberti and all other study authors report no relevant financial disclosures.