Post-mastectomy Radiation Therapy More Effective/necessary In Her2+
 

unclear if only for the her2+er-s or also for the her2+ er+s --will read further

26 March 2008

Postmastectomy radiotherapy not beneficial for all breast cancers

MedWire News: Women undergoing mastectomy for breast cancer only benefit from postoperative radiotherapy if they have hormone-responsive tumors that do not overexpress HER-2, Danish clinicians report in the Journal of Clinical Oncology.

International consensus guidelines recommend postmastectomy radiotherapy (PMRT) only for patients with large tumors and more than three positive lymph nodes, who are considered at increased risk for locoregional recurrence.

However, when examined as single factors, neither nodal status nor tumor size predict survival.

Marianne Kyndi (Aarhus University Hospital) and colleagues investigated the impact of commonly used tumor markers on response to radiotherapy in women who had a mastectomy.

They analyzed primary tumor samples from 1000 women who had undergone a total mastectomy and partial axillary dissection for breast cancer, and randomly assigned 489 to receive PMRT and 511 to receive usual care.

Patients who received PMRT were significantly less likely to die, experience locoregional recurrence, and develop distant metastasis than women who did not receive PMRT, with hazard ratios of 0.84, 0.17, and 0.80, respectively.

When the researchers stratified women according to various clinical parameters they found that this survival benefit of PMRT was almost exclusively seen among women with hormone receptor-positive tumors.

Women with estrogen receptor (ER)-positive tumors who received PMRT were less likely to die of the disease than peers who did not receive PMRT, with a hazard ratio of 0.74.

Conversely, women with ER-negative tumors treated with PMRT were no less likely to die of the disease than their peers who did not receive PMRT, with a hazard ratio of 1.03.

An almost identical trend was observed when considering women with progesterone receptor (PR)-positive breast cancer.

Investigating subtypes further, the researchers found that women with PR-positive and/or ER-positive and HER-2-negative tumors treated with PMRT were less likely to die than their peers who did not receive PMRT, with a hazard ratio of 0.77.

Meanwhile, women with ER-negative/PR-negative/HER-2-positive tumors who received PMRT were statistically no less likely to die than those not treated with PMRT, with a hazard ratio of 1.35.

The researchers conclude by saying that these markers could be useful when selecting patients for PMRT, thereby avoiding skin toxicities.



J Clin Oncol 2008; 26: 1419-1426

http://jco.ascopubs.org/cgi/content/abstract/26/9/1419