I'm a big fan of your reviews JackBauer, but I do not agree with you on that one.
I think the show does a pretty good job by not going too far on the cancer side.
It's a half hour dramedy, and the problem with that format: it does not support well the drama parts.
I think that's why Califonication does so great, and why Hung and Bored to Death did not, by being too serious on their last seasons...
Half hour shows work best when they're mixing more humor than drama. When things go too seriously (like Breaking Bad) it's only good for one hour shows, where everything is more complicated, with more dramatic repercussions, and more psychological insights.
Breaking Bad couldn't be a half hour show like this one.
That's why i think The Big C, despite is high possibility to go into the drama form, should stick with lightness, play with comic situations, and keep the characters far from the pathos, that the cancer will provide.