The Centers for Medicare and Medicaid Services have decided to cover Provenge, a costly vaccine used to treat men with advanced prostate cancer.

Regarding the new drug, CMS says, “The evidence is adequate to conclude that Provenge improves health outcomes for Medicare beneficiaries.”

Unlike other vaccines, Provenge is administered after a diagnosis of prostate cancer and spurs the body’s immune system to attack cancerous cells.

CMS is not supposed to weigh the cost of a treatment when deciding whether it will be covered under a federal entitlement program. However, the agency’s decision to launch a formal examination of the drug, which costs $93,000 per patient, prompted a negative response from drug companies, cancer patients, experts and advocacy groups.

Provenge joins the ranks of new and expensive cancer treatments that appear to extend the lives of patients by mere months, which has prompted outcry about their costs. In the case of Provenge, patients can expect to live an additional four months on average.

The drug, which was approved by the FDA last year, has seen controversy before. In 2007, the FDA delayed its approval, prompting outrage from patients, advocates and investors in the drug’s maker Dendreon. Anonymous death threats, accusations of conflict of interest and congressional lobbying followed swiftly.