Ah! Perfect timing. There I was, not even two months into my five-year prescription for tamoxifen (one of the most "popular" cancer drugs in the world), and already wondering whether the psychologically arduous and physically unpleasant side-effects were really worth it. I'm not the only one who has such thoughts. Research into the medical records of 2,000 breast cancer patients suggests that half of us pack in our daily pill of oestrogen-suppressant before we should. You don't have to be on the stuff for very long to understand why.

But this week the Journal of Clinical Oncology published the results of the first large study comparing five years on tamoxifen to just two years on the drug, over a 10-year follow-up period. The good news is this: it works.

But even good news can be depressing. Cancer returned in 46% of the women who took tamoxifen for two years, but in just 40% of the women who took it for five years. Just 40%? Six fewer in every 100? It's easy to tell yourself, or find other people to tell you, that you'll be OK, that people mostly are these days. Even the professionals tell you, after five years, that you're "clear". The truth? I'm certainly not wasting much time hoping that I'll die before I get old.