A higher intake of protein may be associated with a modest survival advantage in women with breast cancer regardless of insulin receptor status, according to a study published in the Journal of Clinical Oncology.1

Several prospective studies, including the Nurses’ Health Study that evaluated 1982 women, have demonstrated that greater protein consumption is associated with improved breast cancer survival. Researchers hypothesized that protein intake may be more strongly associated in tumors expressing insulin receptor.

For the study, investigators analyzed data from 6348 women with stage I to III breast cancer diagnosed between 1976 and 2004. During follow-up, there were 1046 cases of distant recurrence.

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Results showed that there was 16% reduced risk of recurrence among patients in the highest quintile of energy-adjusted protein intake (relative risk [RR], 0.84; 95% CI, 0.69-1.03) and a 25% reduced risk in the second-highest quintile (RR, 0.75; 95% CI, 0.61-0.91) compared with the lowest quintile.

For animal protein intake, the highest and second-highest quintiles had a 22% (RR, 0.78; 95% CI, 0.63-0.95) and 25% (RR, 0.75; 95% CI, 0.62-0.92) reduced risk of recurrence.

There was no association between essential amino acid intake, branched-chain amino acid intake, or intake of any particular amino acid and risk of recurrence. There was also no clear association for any protein-containing foods.

In addition, researchers found that the association between protein intake and survival did not differ by insulin receptor status.

The findings ultimately suggest that there is no advantage for women with a history of breast cancer in restricting protein intake or protein-containing foods.


1. Holmes MD, Wang J, Hankinson SE, Tamimi RM, Chen WE. Protein intake and breast cancer survival in the Nurses’ Health Study. J Clin Oncol. 2016 Nov 7. doi: 10.1200/JCO.2016.68.3292. [Epub ahead of print]