Can you donate blood/organs if you've had cancer/chemotherapy?

May be: The blood banks use a number of criteria to check for suitability to donate blood. Having chemotherapy per se is not a disqualification. See this site for more info. http://www.redcrossblood.org/donating-blood/eligibility-requirements.

Depends: Each donor is assessed for risk factors based on his/her individual medical and social history. For patients with a history of cancer, the decision to accept them as a donor depends on the type and stage of the cancer, the time from occurrence to donation, and testing to see whether there is evidence of recurrence. In addition, the immediate need for an organ may sometimes be considered.