Jane Tomlinson, who is living with advanced breast cancer, starts her grueling 4200 mile, US-spanning bike ride to raise money for cancer research this Friday in San Francisco. According to her Website, she?s run three London marathons, the NYC marathon, and completed the Ironman triathalon among other extreme exercise fundraisers since she was told nearly six years ago that she had six months to live. She?s been quoted as saying that she expects this to be the most difficult trek of her life. I bet she?ll recall that prediction climbing above the 10,000-foot mark in the Rockies.

In many tumor microenvironments, a hypoxic state or genetic changes may trigger activity of the hypoxia inducible factor (HIF), a transcription factor that turns on a slew of genes for angiogenesis and may turn off DNA repair. The tumor essentially fools the body into thinking it needs more oxygen at the site of the tumor. But as often seems the case with cancer, the same signal often has opposite effects. While her journey into thin air would likely trigger HIF, hypoxic conditions and hyperthermia have been linked to tumor death. Tomlinson?s truly a unique individual, of course. I?m amazed that someone undergoing chemo can find the energy she has, and she serves as an inspiration. (I couldn?t help but donate a little for a fellow biker.) I wonder, however, what kind of effects extreme exercise in hypoxic conditions have on tumor growth.