Format

Send to

Choose Destination
Acta Oncol. 2018 Jan;57(1):38-43. doi: 10.1080/0284186X.2017.1401735. Epub 2017 Nov 25.

Intrinsic subtypes and benefit from postmastectomy radiotherapy in node-positive premenopausal breast cancer patients who received adjuvant chemotherapy - results from two independent randomized trials.

Author information

1
a Department of Experimental Clinical Oncology , Aarhus University Hospital , Aarhus , Denmark.
2
b Department of Pathology , Aarhus University Hospital , Aarhus , Denmark.
3
c British Columbia Cancer Agency , Vancouver , British Columbia , Canada.
4
d Department of Genetics, Institute for Cancer Research , Oslo University Hospital , Oslo , Norway.
5
e Lineberger Comprehensive Cancer Center , University of North Carolina , Chapel Hill , NC , USA.
6
f Department of Medical Oncology , Hospital Clinic , Barcelona , Spain.
7
g Institut d'investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) , Barcelona , Spain.
8
h Clinical Trials and Statistics Unit , Institute of Cancer Research , London , UK.

Abstract

BACKGROUND:

The study of the intrinsic molecular subtypes of breast cancer has revealed differences among them in terms of prognosis and response to chemotherapy and endocrine therapy. However, the ability of intrinsic subtypes to predict benefit from adjuvant radiotherapy has only been examined in few studies.

METHODS:

Gene expression-based intrinsic subtyping was performed in 228 breast tumors collected from two independent post-mastectomy clinical trials (British Columbia and the Danish Breast Cancer Cooperative Group 82b trials), where pre-menopausal patients with node-positive disease were randomized to adjuvant radiotherapy or not. All patients received adjuvant chemotherapy and a subgroup of patients underwent ovarian ablation. Tumors were classified into intrinsic subtypes: Luminal A, Luminal B, HER2-enriched, Basal-like and Normal-like using the research-based PAM50 classifier.

RESULTS:

In the British Columbia study, patients treated with radiation had an overall significant lower incidence of locoregional recurrence compared to the controls. For Luminal A tumors the risk of loco-regional recurrence was low and was further lowered by adjuvant radiation. These findings were validated in the DBCG 82b study. The individual data from the two cohorts were merged, the hazard ratio (HR) for loco-regional recurrence associated with giving radiation was 0.34 (0.19 to 0.61) overall and 0.12 (0.03 to 0.52) for Luminal A tumors.

CONCLUSIONS:

In both postmastectomy trials, patients with Luminal A tumors turned out to have a significant lower incidence of loco-regional recurrence when randomized to adjuvant radiotherapy, leaving no indication to omit postmastectomy adjuvant radiation in pre-menopausal high-risk patients with Luminal A tumors. It was not possible to evaluate the effect of radiotherapy among the other subtypes because of limited sample sizes.

PMID:
29172851
DOI:
10.1080/0284186X.2017.1401735
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Taylor & Francis Icon for Norwegian BIBSYS system
Loading ...
Support Center