I think it was because no other doctors wanted to operate on it, I think she had prior surgeries to remove other cancer thingys but one was close to her spine so doctors didnt wana remove it in case it made her paralysed or something - I think this mite have been the one that got big.
On the topic of why people dont get them removed, there was a similar case on RPA. An elderly woman had a tuma nthingy inside her, making her look like she was pregnant, it was the size of a water melon and filled with liquid stuff. Why she didnt go to a doctor earlier has be puzzled, did she think she was pregnant at like 80 or something!?