Less Chemo Fatigue. Why?

The latest round of chemo produced significantly less chemo fatigue than normal. Usually, the fatigue begins on Friday evening after my Wednesday infusion and continues through Saturday and Sunday, and then lifts through about mid-week, so that by Thursday, I am most of the way back to normal. This time, I had only minimal fatigue on Saturday and Sunday. Why?

Three possible factors come to mind:

1. Current thinking about chemo fatigue suggests that it is caused, at least in part, by substances called cytokines that are released into the bloodstream by dying cells. It's like the body is telling you, “Hey, you're injured. Find a place of retreat where you can lick your wounds and heal.”

I have an hypothesis that when I begin a new series of chemo after a break (11 months this last time), the chemotherapy agent, pemetrexed, has lots of vulnerable cancer cells to kill, so lots of cytokines are released producing lots of fatigue. Given that pemetrexed only works on actively dividing cells, not all vulnerable cancer cells are killed with the first infusion, so there is a new crop of dividing cells ready to be killed by the next dose three weeks later. It seems to me that there would be fewer cells left that are sensitive to pemetrexed with each infusion; consequently, the fatigue would fade in severity. I have my next CT in a couple of weeks, and my guess is that my tumors will not have shrunk much, if at all, because six round of pemetrexed have gathered all the low-hanging fruit.

2. Perhaps the extra energy from the supplemental oxygen reduced the fatigue.

3. We started a new tradition this spring, and Jana makes me a “chemo cake” each time I have an infusion. This time, however, I got a chemo car instead of the cake. I bought a red, first generation Mazda Miata sports car. Do you think the new car helped fight the fatigue better than a cake?