How safe is blood transfusion?

During a casual conversation, a friend asked me if I believe that cancer is closely associated with the type of blood groups. She read about the correlation between them from a book. I do not buy the author's theory but my friend believes in it. Out of curiosity, I asked her - "Which blood group is the best?" She told me the author claimed that it was blood group "O". Coincidentally, my late mother's blood group was "O" type. Well, she remains unconvinced and will try to gather more data to support the author's claims.

As we chatted, I shared with her my concern about the danger of contracting cancer from blood transfusions. In order to clear my doubts, I wrote to the Health Sciences Authority (HSA) to seek clarification. I reckon it is helpful information and decided to share the replies that I received from HSA.

I posed the following query to HSA.

Please let me know if blood donated by donors who are already having cancerous cells will affect the recipients. Very often, cancer is diagnosed at its late stage. Hence the donors may not know about their illness when they donate their blood. Are such donors required to inform HSA about their cancer diagnosis?

Reply #1 :

Thank you for your email dated July 10, 2008.

At present, we do testing for infectious diseases that can be transmitted by blood, which includes HIV, Hepatitis B and C, Syphilis and malaria. We do no test for cancer markers to check for a possible malignancy. This is the accepted standard of practice locally as well as in other developed countries like in the United States and United Kingdom.

There is no way to know whether potential donors harbor a malignancy that will be diagnosed within the ensuing few years, That is why in our medical screening, we always ask about the health condition and history of our blood donors. If there is any hint or doubt of a possible tumor or malignancy, we advise the donor to see a specialist. Once they have been diagnosed to have a cancer, they are not allowed to donate.

In connection with your question, there was a recent study published in the Lancet medical journal (May 19, 2007) regarding the risk of transmitting cancer through blood transfusion and the authors concluded that based on their data, there is no evidence that blood transfusions from precancerous blood donors are associated with increased risk of cancer among recipients compared with transfusions from non-cancerous donors.

We hope we have managed to clear your doubts and look forward to serving you in the near future.

Reply #2

Regarding your concern about cancer cells being transfused, in theory what happens is any foreign cells (e.g. cancer cells) that enter the bloodstream will be detected by the immune system and destroyed. Literature regarding this matter is very scarce and is considered a "gray area". That is why for safety concerns, it is best that donors who have been diagnosed with cancer are advised not to donate. This policy is also being implemented in other developed countries.

Donors are advised to inform us if they have been diagnosed with any illness especially cancer and other infectious diseases even after they have donated blood. This can be done through email or telephone 1800-2263320 (toll-free).

Hope I have answered your query.