I have just come across this article:
Chemotherapy is more effective when the first dose coincides with a particular phase of the reproductive cycle. Female mice with breast cancer responded better to chemotherapy when they were in the estrus stage of their 4-5 day reproductive cycle, which is when progesterone levels are at their lowest and the mammary cells proliferate in preparation for pregnancy. A study of 25 people with an aggressive form of breast cancer showed a similar pattern, with chemotherapy working better when people had low progesterone levels. As chemotherapy disrupts the menstrual cycle, this synchronization would only be possible for the first dose.
The Scientist | 4 min read
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Reference: Nature paper (4 December)
