New York, March 2 (IANS): Low levels of vitamin D in men can predict aggressive prostate cancer identified at the time of surgery, new research has found.

The finding is important because it can offer guidance to men and their doctors who may be considering active surveillance, in which they monitor the cancer rather than remove the prostate.

"Vitamin D deficiency may predict aggressive prostate cancer as a biomarker," said lead investigator Adam Murphy, assistant professor of urology at Northwestern University Feinberg School of Medicine in Chicago, US.

Previous studies showing an association between vitamin D levels and aggressive prostate cancer were based on blood drawn well before treatment.

The new study, published in the Journal of Clinical Oncology, provides a more direct correlation because it measured vitamin D levels within a couple of months before the tumour was visually identified as aggressive during surgery to remove the prostate.

Because vitamin D is a biomarker for bone health and aggressiveness of other diseases, all men should check their levels, Murphy said.

Aggressive prostate cancer is defined by whether the cancer has migrated outside of the prostate and by a high Gleason score -- used to help evaluate the prognosis of men with prostate cancer.

A low Gleason score means the cancer tissue is similar to normal prostate tissue and less likely to spread while a high one means the cancer tissue is very different from normal and more likely to spread.

The study was part of a larger ongoing study of 1,760 men in the Chicago area examining vitamin D and prostate cancer.

The current study included 190 men, average age of 64, who underwent a radical prostatectomy to remove their prostate from 2009 to 2014.

Of that group, 87 men had aggressive prostate cancer.

Those with aggressive cancer had a median level of 22.7 nanograms per millilitre of vitamin D, significantly below the normal level of more than 30 nanograms/millilitre.

The average vitamin D level in Chicago during the winter is about 25 nanograms/milliliter, Murphy noted.