12th May 2024

A 70-year-old man presents with progressive fatigue, weight loss, and a change in bowel habits over the last four months.

A 70-year-old man presents with progressive fatigue, weight loss, and a change in bowel habits over the last four months. He has a personal history of type 2 diabetes and a family history of colorectal cancer. A colonoscopy reveals a circumferential mass in the sigmoid colon, and a biopsy confirms mucinous adenocarcinoma. A subsequent PET scan demonstrates local invasion into the bladder but no distant metastases.

Which is the most likely route by which this tumour spread to the bladder?