I just read this in the Astral Codex Ten post of links for February. I haven't looked into it at all myself or even read the report itself. (And Scott doesn't explicitly say 'Givewell', I'm just assuming that's what he means by "effective altruists have tentatively found one or two opportunities in the poorest parts of Africa to save lives at $100/DALY"). From Astral Codex Ten:
Study: federal cancer funding is extraordinarily effective. Cancer research produces so many valuable treatments that it saves one DALY per $326 spent. For comparison, health systems usually consider an intervention good value-for-money if it saves at least one DALY per $50,000. By combing the Earth far and wide, effective altruists have tentatively found one or two opportunities in the poorest parts of Africa to save lives at $100/DALY, but these are extremely rare exceptions and I wouldn’t have expected anything in the US to be within an order of magnitude of that. Either this finding is fake, or we should all be donating to federal cancer research instead of whatever else we’re doing.
(I should also note Scott's disclaimer at the top of his post: I haven’t independently verified each link. On average, commenters will end up spotting evidence that around two or three of the links in each links post are wrong or misleading. I correct these as I see them, and will highlight important corrections later, but I can’t guarantee I will have caught them all by the time you read this)