Mastectomy alone for pT1-2 pN0-1 breast cancer patients: when postmastectomy radiotherapy is indicated

A three-gene signature marks the time to locoregional recurrence in luminal-like breast cancer

BACKGROUND

Gene expression profiling (GEP)-based prognostic signatures are being rapidly integrated into clinical decision making for systemic management of breast cancer patients. However, GEP remains relatively underdeveloped for locoregional risk assessment. Yet, locoregional recurrence (LRR), especially early after surgery, is associated with poor survival.

PATIENTS AND METHODS

GEP was carried out on two independent luminal-like breast cancer cohorts of patients developing early (≤5 years after surgery) or late (>5 years) LRR and used, by a training and testing approach, to build a gene signature able to intercept women at risk of developing early LRR. The GEP data of two in silico datasets and of a third independent cohort were used to explore its prognostic value.

RESULTS

Analysis of the first two cohorts led to the identification of three genes, CSTB, CCDC91 and ITGB1, whose expression, derived by principal component analysis, generated a three-gene signature significantly associated with early LRR in both cohorts (P value <0.001 and 0.005, respectively), overcoming the discriminatory capability of age, hormone receptor status and therapy. Remarkably, the integration of the signature with these clinical variables led to an area under the curve of 0.878 [95% confidence interval (CI) 0.810-0.945]. In in silico datasets we found that the three-gene signature retained its association, showing higher values in the early relapsed patients. Moreover, in the third additional cohort, the signature significantly associated with relapse-free survival (hazard ratio 1.56, 95% CI 1.04-2.35).

CONCLUSIONS

Our three-gene signature represents a new exploitable tool to aid treatment choice in patients with luminal-like breast cancer at risk of developing early recurrence.

A propensity score-matched analysis of breast-conserving surgery plus whole-breast irradiation versus mastectomy in breast cancer

PURPOSE

Recent observations regarding long-term outcomes among patients with early-stage breast cancer (BC) who underwent breast-conserving surgery (BCS) plus whole-breast irradiation (WBI) or mastectomy are from a small number of registry-based studies. Therefore, these findings may overestimate differences in survival between the two groups, compared with randomized controlled trials conducted in the 1980s. The aim of this study is to compare long-term outcomes and clinicopathologic characteristics between patients treated with BCS + WBI or mastectomy for BC.

METHODS

We performed a propensity score-matched analysis in a cohort of 9710 patients aged < 70 years who underwent BCS + WBI or mastectomy without external radiotherapy for a first primary BC (pT1-2, N0-3a) at the European Institute of Oncology between 2000 and 2008. Patients were matched by propensity score.

RESULTS

Median follow-up was 8.4 years (interquartile range 6.5-10.2). The cumulative incidence of axillary lymph node recurrence at 10 years was lower in the BCS + WBI group [2.4% (95% CI, 1.7-3.3%)] than in the mastectomy group [4.4% (95% CI, 3.5-5.5%)] (P = .0005), and the cumulative incidence of contralateral BC was higher in the BCS + WBI group [3.9% (95% CI, 2.8-5.1%)] than in the mastectomy group [2.5% (95% CI, 1.7-3.4%)] (P = .01). Among the 366 patients with HER2 subtype BC, BCS + WBI was associated with a fivefold higher risk [hazard ratio 4.97 (95% CI, 2.28-10.8)] of  ipsilateral breast tumor recurrence (IBTR), compared with mastectomy (P < .0001); however, among patients with other BC subtypes, the rates of IBTR were not statistically significantly different.

CONCLUSION

Patients with HER2 subtype BC (T1-2, N0-3) who underwent BCS + WBI had a statistically significantly higher risk of IBTR than patients who underwent mastectomy. Survival was not statistically significantly different between the groups.

Debate: Postmastectomy Radiation Therapy in T1/2N1 Disease

Although postmastectomy radiation therapy is known to reduce local recurrence in patients with T1/2N1 breast cancer, some have postulated that not all patients require this treatment. In this era of genomic analyses and personalized therapy, clinicians have debated whether the toxicity of post-mastectomy radiation therapy (PMRT) can be avoided for some subsets of patients. However, the data in this regard remain controversial, particularly as surgeons de-escalate the surgical management of the axilla. Several ongoing clinical trials may provide a glimpse into optimal management in this scenario. However, the "right" answer to this debate currently remains unclear.