A key to unlocking the mystery of triplenegative breast cancer24 October 2016

Micrograph showing a lymph node invaded by ductalbreast carcinoma, with extension of the tumour beyondthe lymph node. Credit: Nephron/Wikipedia

A study conducted at the Research Institute of theMcGill University Health Centre (RI-MUHC)suggests screening breast cancer patients for theprolactin receptor could improve the prognosis forpatient and may help them avoid unnecessary andinvasive treatments. Using a database of 580women with triple negative breast cancer (TNBC),the researchers found that survival was prolongedin patients who expressed the prolactin receptorand that prolactin hormone was able to reduce theaggressive behavior of cancerous cells. It does soby decreasing their ability to divide and form newtumors. The research was published in the journal Scientific Reports.

TNBC refers to a tumor that is estrogen receptor-negative, progesterone receptor-negative andHER2-negative. "TNBC is the most aggressivetype of breast cancer and it is very difficult to treat,"explains Dr. Ali, a researcher from the Cancer

Research Program at the RI-MUHC and lead authorof the study. "While prognosis and treatmentoptions for breast cancer patients as a whole haveimproved in recent decades, this is not true forwomen who develop TNBC - they still have limitedoptions for targeted treatment strategies, oftenrequire invasive chemotherapy and have a poorprognosis."

The reason for this is that TNBC cancers arediverse and do not behave in the same manner inall patients, something that researchers have notfully understood. However, Dr. Ali's team may havefound the key to unlock this mystery. Theydiscovered that women with tumors that expressthe prolactin receptor had a less aggressive breastcancer and a far better prognosis. Furthermore, in apreclinical animal model, they determined that if theprolactin receptor was not present, the tumor cellswere not just more aggressive, but also proliferativeand invasive compared with the ones that expressthe prolactin receptor.

The results suggest that screening for the prolactinreceptor could indicate which patients might benefitfrom prolactin treatment as a single agent, or incombination with less aggressive chemotherapy,"explains Dr. Ali. "We think this could be arevolutionary path to developing new treatments forbreast cancer.".

Women's health and prolactin

The role of prolactin in breast cancer is not fullycharacterized and still controversial. Betterunderstanding of its role in cancer could havedirectly impact in doctor advice to patients with highrisk of developing breast cancer to practicebreastfeeding as a protective measure. Thesefindings are consistent with past studies suggestingthat prolactin has a suppressing effect on breastcancer. Dr. Ali states "our research supports thatbreastfeeding is not only beneficial for infants butalso for the mothers. Since breastfeeding is a

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natural way to produce prolactin in high levels,breastfeeding would actually reduce a woman's riskof developing breast cancer".

More information: Prolactin Pro-DifferentiationPathway in Triple Negative Breast Cancer: Impacton Prognosis and Potential Therapy, ScientificReports, 2016.

Provided by McGill University Health CentreAPA citation: A key to unlocking the mystery of triple negative breast cancer (2016, October 24) retrieved26 July 2018 from https://medicalxpress.com/news/2016-10-key-mystery-triple-negative-breast.html

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