Fungating breast tumors are so sad. The delay in seeking treatment is often a shame issue; the patient clearly
knows there is something badly wrong but doesn't seek treatment because of the horrifying nature of such a condition. These tumors look and smell absolutely disgusting, which makes people wary of seeking medical attention. These tumors usually affect older women, who were likely socialized to treat their bodies as something to be hidden even when healthy. Having a legitimately repulsive condition is shameful and embarrassing.
It's sort of a denial thing, too, like "maybe if I just ignore this it's not as terrible as it looks and will go away on its own", even if on an intellectual level the patient understands that it is a serious problem requiring professional care. Sometimes when a person has a disfiguring condition, it's almost as though their body becomes foreign to them, like it's no longer theirs. I think that contributes to the apparent lack of urgency in seeking treatment, too - it sort of feels like it's happening to someone else.
Additionally, once the tumor is fungating, the person is imminently terminal and I think on an unconscious level they accept that they're dying and don't feel an urgent need for medical help despite the very obvious gravity of their physical condition. There is a phenomenon called
la belle indifference which is fairly common in patients with conversion disorder/"functional neurological disorder" and refers to these patients' lack of psychological distress proportional to the severity of their physical symptoms. Like I said, it is associated with conversion disorder, but I personally think it happens in cases of severe injury or terminal illness, too. It's like the lizard brain is trying to minimize the patient's agony because there's no point to it anyway. It's how you get people calmly walking into the ER with their leg rotting off or a tumor eating through their chest.
Anyway, I digress.