By Lynda Williams, medwireNews Reporter
medwireNews: For women undergoing breast-conserving surgery for invasive breast cancer, omission of axillary sentinel lymph node (SLN) biopsy offers noninferior 5-year invasive disease-free survival (iDFS) compared with standard axillary surgery, say the INSEMA trial investigators.
“This de-escalation concept may be suitable for patients 50 years of age or older who present with low-risk (grade G1 or G2), [hormone receptor]-positive, HER2-negative invasive breast cancer and clinical T1 tumors”, write Toralf Reimer (University of Rostock, Germany) and co-authors in The New England Journal of Medicine.
The per protocol population of the study included 4858 patients with clinically node-negative, T1 or T2 invasive breast cancer no larger than 5 cm in size who were scheduled to undergo breast-conserving surgery. All the patients underwent postoperative whole-breast radiotherapy, with a tumour bed boost recommended.
After a median 73.6 months of follow-up, the estimated 5-year iDFS rate was 91.9% among the 962 patients who were randomly assigned to undergo surgery without axillary SLN biopsy versus 91.7% for the 3896 patients who underwent biopsy.
This gave a nonsignificant hazard ratio (HR) for local, axillary or distant invasive disease recurrence, contralateral invasive breast cancer, second primary invasive cancer, or death from any cause of 0.91. This was below the prespecified margin for noninferiority of omitting axillary SLN biopsy, Reimer et al report.
They note that there was a “broader confidence interval” for patients with T2 versus T1 disease (HR=0.71 and 0.95) but the findings were “generally consistent”.
The estimated 5-year overall survival rates in the omitted axillary surgery and axillary surgery groups were 98.2% and 96.9%, respectively, with a nonsignificant HR for death of 0.69.
Overall, 10.8% of patients in the study experienced occurrence, recurrence or death, and analysis indicated that women who did not undergo axillary SLN biopsy had a higher rate of axillary recurrence than those who did (1.0 vs 0.3%) but a lower rate of death (1.4 vs 2.4%).
In multivariate Cox regression analysis, age above 65 years, preoperative tumour size greater than 2 cm and a grade 3 tumour were significant risk factors for poor iDFS.
Finally, analysis indicated that patients who did not undergo axillary SLN biopsy were less likely than those who did to experience lymphoedema (1.8 vs 5.7%), arm or shoulder mobility restrictions (2.0 vs 3.5%) and pain (2.0 vs 4.2%).
Writing in an editorial accompanying the research, Monica Morrow (Memorial Sloan Kettering Cancer Center, New York, USA) says that the INSEMA findings, in combination with the earlier SOUND trial that also demonstrated noninferior survival with SLN omission for patients undergoing breast-conserving surgery, “provide a glimpse into the future.”
She acknowledges that omitting SLN biopsy reduces the “treatment burden on patients”, but she questions whether the resulting “uncertainty about nodal status” may compromise decisions on the use of adjuvant therapy, CDK4/6 inhibitors and whole-breast versus partial-breast irradiation.
“At present, patients with grade 1 or 2, cT1 tumors are ideal candidates for [SLN biopsy omission]”, Morrow writes.
“If surgical pathological examination reveals a larger T2 tumor, a high-grade tumor, or lymphovascular invasion — factors that increase the likelihood of nodal metastases and are indicative of worse prognosis — patients can then undergo sentinel-lymph-node biopsy”, she proposes.
“This approach will avoid axillary surgery for the majority while minimizing undertreatment.”
The commentator concludes: “Patient-reported outcomes are needed to determine which therapies patients prefer to de-escalate as we increasingly face a choice of which therapies to omit.”
News stories are provided by medwireNews, which is an independent medical news service provided by Springer Healthcare Ltd. © 2024 Springer Healthcare Ltd, part of the Springer Nature Group
N Engl J Med 2024; 12 December
Pubmed https://pubmed.ncbi.nlm.nih.gov/39665649/
N Engl J Med 2024; 12 December