KLK3 and prostate cancer: Initial screens for prostate cancer include digital rectal examination (DRE) and measurement of serum prostate specific antigen (PSA).31 Neither of these methods are highly specific or predictive, so they are used in combination with other symptoms and family history before a patient is suspected to have cancer.26,32 Globally, invasive breast cancer is the most common type of cancer affecting women, but it has a good prognosis if detected early.