|I think there could be more imagery in the first stanza and even the second. I think I'm just looking for more details, more specifics. I know what a port looks like because my dad has cancer, but I'm not sure if your description would get the idea across to someone who hadn't seen it.
I don't know if I like the cynicism here. I don't think it carries the topic as well. It seems like the focus starts out being the reality of cancer, but it seems to snowball into a rant (of sorts) about cigarettes, which really doesn't say anything we haven't heard before.
I believe that saying this:
Fed by a cigarette,
Bit by bit,
Month by month,
Year by year.
maybe with a few extra lines would be sufficient to cover the cigarettes then return to describing cancer itself - the balding, etc.
Alternatively, you could more furtively include the idea of cigarettes into the poem by metaphorically weaving aspects of smoking into other descriptions. "Life fading like smoke" - something like that. You get my drift. The layering would perhaps tone the cynicism down a bit.
Anyway, I think this has a lot of good aspects to it. I did find it to be a good read. The second stanza is the strongest I believe. I think you should rework parts of it, and that could be because I would approach the topic differently. Good luck with this!