"At the Hospital" by David Ferry

David Ferry was born in 1924 in Orange, New Jersey. He is an American poet, translator, and educator, and he has published eight volumes of poetry and a volume of literary criticism.

She was the sentence the cancer spoke at last,
Its blurred grammar finally clarified.

This poem is incredibly short, but so much is packed into one sentence. Cancer is a heavy topic: we don't like to talk about it, and when we do, there's not much good to say about it, until you get to the people who have survived or know survivors. Those people are the ones that constantly instill hope and positivity in us, but nothing about this poem breathes anything good.
The past tense "was" implies that the woman whose diagnosis is cancer is now gone. She has passed on, and the cancer won in the end. The "blurred grammar" that is finally "clarified" is generally confusing. It seems that the woman's death made cancer's sentence become understandable.
Cancer can appear rapidly, and it can take lives rapidly, but it seems that this end was foreshadowed some time ago. The "at last" could be like some breath of relief - relief that the suffering is over. Then again, the fact that we know that this woman has passed could mean that cancer only truly showed itself when she had died. The cause of death was cancer, but it is possible that it was only known that she had cancer afterwards.
Maybe the clarification determined is that there is no answer to cancer. There are the very lucky survivors, but there is not an answer to every type of cancer, and this type, whatever it may be, clarifies this overall. Clarification tends to be something we want - we want to be able to understand everything around us -, but here, the clarification of cancer's "blurred grammar" doesn't seem desirable. It seems upsetting, and it's paradoxical.
Yet the poem is so abrupt that it makes every single word more powerful, which makes this poem not so much about the woman lost but about the sentence itself. This sentence lets cancer be personified. Cancer is talking here, and cancer is in control.