Specific viruses may be associated with increased risk and worse outcomes of ovarian cancer

1. This retrospective cohort study tested ovarian tumors for 113 viruses and found six viruses of interest (VOIs) that were present in one-quarter of tumors.

2. The presence of one of these VOIs was associated with a four-fold decrease in overall survival (OS) compared to those with any other viral strain or no viral strains. This finding did not apply to women above the age of 70, however.

Evidence Rating Level: 2 (Good)

Infectious agents are thought to cause just shy of one-fifth of cancer cases globally, and thus far, ovarian cancer is not known to have an infectious etiology. Internationally, eleven infectious organisms are currently classified as carcinogenic. However, one such infectious agent, human papillomavirus (HPV), is often found in ovarian tumors. The literature has not elucidated whether this takes place after the development of cancer or prior to it, but there is data to suggest that the expression of viral microRNA in tumors could be associated with worse clinical outcomes. Thus, this current study sought to assess whether ovarian tumors commonly carried viruses and whether presence of viruses in ovarian tumors was associated with decreased overall survival (OS). Tumor cells were analyzed from 98 patients (archived tumors) and any tissue that had been exposed to chemotherapies were excluded. The samples were tested by polymerase chain reaction (PCR) to detect 113 infectious agents. Results indicated that 46.9% of all samples contained at least one virus, and the most common viruses identified included herpesviruses EBV1 and HHV6b, polyomavirus MCPyV, a gamma HPV type (HPV4), a beta HPV types (HPV23), and one mucosal high-risk HPV (HPV16). In high-grade serous epithelial cancer, the most common histology of ovarian cancer, one or more of these six viruses of interest (VOI) were present in one quarter of tumors. Overall, patients with tumors containing any of these VOIs had a four-fold worse OS than those with other infectious agents or no virus present (HR 4.11, p = .0001; median survival 22 versus 44 months). This difference was no longer significant in women over the age of 70 (p > .05). Other factors also associated with lower OS included older age and advanced stage at diagnosis. Overall, these results indicate that viral infiltration of ovarian tumors may have implications for survival, but future studies should elucidate whether or not there is an element of reverse causation between these viruses and cancers.

Click to read the study in PLOSONE

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