Should women take hormone replacement therapy if they have a history of cancer?

Depends. Women with history of breast cancer may or may not be given the ok to take estrogen. Some endometrial cancer cases can take ht after @ cancer free yrs. Should not affect other cancers. Best to seek counsel with your md.
Depends. What type of cancer? I will assume you are talking about breast cancer. There are many factors that contribute to an appropriate answer such as how far out are you, are you dealing with quality of life issues that require hrt, etc. My suggestion is to work closely with a physician who is well versed in both oncology and hrt. I work locally with a well known oncologist who treats high risk wome.