Cancer not contagiou. Cancer can spread within one's body, but not to another person. So, as far as "blood cancer" is concerned, that should not a be a reason not to have relation. Bloodborn infections..Hiv/syphillis, and lowly-possibly hepc, and tissue/skin infections i.e.Herpes/hpv etc..Are of concern. So caution is advised about infections but not about cancer. If u r still concerned, consult your doc. Good luck.