A new study of Israeli men has found that those who have fathered daughters but no sons have a 40 percent higher risk of prostate cancer than men with at least one male offspring. The study raises the possibility that a mutation or variant of the Y chromosome, which only males have, may be involved in prostate cancer. Although several studies have identified risk factors and gene mutations associated with the disease, none of these can account for large numbers of prostate cancer cases. Studies have suggested that prostate cancer risk may be associated with alterations on the X or Y chromosomes. Men have X and Y chromosomes, while women have only X chromosomes. The male determines the sex of his offspring, depending on whether his fertilizing sperm carries an X or a Y chromosome. Because alterations on the sex chromosomes might affect the probability of having sons or daughters, Columbia University Prof. Susan Harlap decided to study cancer incidence and offspring among men participating in the Jerusalem Perinatal Study conducted by researchers at the Hebrew University-Hadassah Braun School of Public Health and Community Medicine. The research looked at more than 38,000 Israeli men and compared the families of the 712 diagnosed with prostate cancer with those of the other study participants. Compared with men who had at least one son, men with only daughters had a 40% higher risk of prostate cancer. Men with no daughters were at greater risk for the disease than those with offspring of both genders. The study suggests the increased risk may be caused by something in the male Y sex chromosome, not the act of having either a son or daughter. Since prostate problems are often only detected when a man goes for routine health screening, the researchers suggests that perhaps having a predominantly female family might encourage men to go to the doctor to find out if he had a health problem preventing him from siring a son. It would be unfair to blame prostate cancer on one's daughters, the researchers said. However there is no evidence to support such an hypothesis, and the researchers suggested that a genetic cause could be contributing to both the birth of daughters and the risk of cancer. Faults on men's Y chromosomes could affect the likelihood of conceiving sons as well as lead to cancer development, the authors of the study said, adding that they could not offer advise to men until major genetic studies on the matter were conducted.