More evidence of the positive role that exercise plays in recovery from this review of a number of different studies that showed, whatever the methodology, regular physical activity “decreased the risk of cancer-related mortality and of all-cause mortality”.
Specifically, “exercise tended reliably to improve insulin levels, reduce inflammation, and increase populations of immune system cells”.
And no surprise to me, any activity, such as walking, is fine – no need for anything more vigorous.
Phys Ed: Cancer Survivors Who Exercise Live Longer – NYTimes.com.

Not surprising but confirms experience and common sense. Conclusion: