Does cancer occur more frequently among married or unmarried women?

Reports from death certificates show that above the age of 40, the cancer death rate is higher among single women than among married women of the same ages. 

Single women have higher death rates from cancer of the breast and married women have more cancer of the uterus. 

Physicians believe that having the first child around the age of 20 is a preventive against cancer of the breast and that injury at child birth or having multiple sexual partners increases the risk of cancer of the uterus.