>some other variable that incidentally varies by time of day.
glucose level? low in the morning, and cancer likes glucose (among other effects of low glucose a cancer site would probably have lower local acidity, and the high local acidity is one of the tools used by cancer to protect and spread itself) .
AM/PM glucose differences are probably going to be swamped by mundane stuff like who has a snack before treatment vs. who doesn't. Are you not supposed to eat before immunotherapy? If so, maybe (non)compliance with that requirement is what's underneath.
i'd think the local acidity (build up of lactic acid resulting from glucose over-consumption by the cancer cells) would take a bit to build back up once glucose ups after the night.
glucose level? low in the morning, and cancer likes glucose (among other effects of low glucose a cancer site would probably have lower local acidity, and the high local acidity is one of the tools used by cancer to protect and spread itself) .