Viagra refers to sildenafil and this product does not treat cancer. Sildenafil is used to treat erectile dysfunction is a male drug, sildenafil has no role in treating cancer. Cancer is usually treated with surgery, radiotherapy, targeted, immunization and many other means, not with male erectile dysfunction type of medicine. Adverse reactions of sildenafil include chills, shock, fatigue, pain, edema, abdominal pain, rash, pruritus, palpitations, tachycardia, syncope, migraine, arthritis, synovitis, neuralgia, and sensory abnormalities. It is forbidden for patients who are allergic to this product, and people with allergies should use it with caution. Cancer patients can not self-medication, do not blindly take sildenafil, if improper use of medication to appear unwell should be actively seek medical attention, under the guidance of the physician’s interview in accordance with the norms of treatment.