A clustering of the disease among close relatives has also been shown, although there is no consensus on which inheritable genetic defects are involved. In spite of extensive research, reliable findings on risk factors relating to lifestyle, diet or the environment remain elusive. Possible lifestyle risk factors are high intakes of α-linolenic acid (a polyunsaturated fatty acid in vegetables and dairy products) and calcium. Common risk factors for various cancer sites such as tobacco smoking, alcohol consumption and low physical activity do not seem to affect prostate cancer risk (Grönberg, 2003; Patel & Klein, 2009)
