The drug sildenafil, better known as Viagra has been shown in mice to support the immune system's response to cancer cells. Mice with colon and breast tumors showed that the tumor size decreased two and threefold when treated with sildenafil compared with the mice that did not receive the drug. The researchers also believe that they have evidence that sildenafil is effective on the immune system because in mice engineered to lack an immune system the tumors were unaffected. Tissue samples taken from head and neck cancer and multiple myeloma patients showed similar results.

Viagra is a class of drugs used to treat impotence. It is known to stimulate nitric oxide which hinder the effects of a specialized cell that can divert the immune system away from the tumor. The researchers are trying to figure out how cancer cells can avoid detection by the immune system. T-cells that mount the attack on cancer cells are manipulated by the cancer cells and prevent them from being seen by the immune system. Viagra can unmask the cancer cells and let the immune system recognize and attack them.

Only half of prostate cancer survivors who suffer from erectile dysfunction (ED) said that it was an issue that concerns them, according to a survey conducted by Harvard Medical School in Boston researchers, and therefore do not speak with the doctor about sexual difficulties or ask for help with therapy that might make a difference -- like being prescribed Viagra.

In this study the researchers learned that it also depends on the type of prostate cancer treatment that influenced whether a man was bothered by ED. Over 75 percent of men who underwent radical prostatectomy asked for help the most; about 50 percent of men who were treated with brachytherapy asked for help; and less than 40 percent of men who were treated with external beam radiation spoke with the doctor about ED in expressing concern about sexual difficulties.

Researchers explained that men who undergo radical prostatectomy will experience a sudden loss of ability to achieve an erection, and then erectile function gets better. But for men who are treated with radiation therapy, the erectile dysfunction problems gradually worsen over time, and these are the men most likely not to speak about it.

According to the researchers, "Additional study is clearly warranted to clarify whether radiotherapy patients are simply more accepting of treatment-induced declines in sexual function or if their less frequent use of such assistance measures represents an important, and unmet, healthcare need."