eP423 - Synchronous Colon and Breast Adenocarcinoma in a Male Patient

Purpose/Background: Synchronous cancers refer to the occurrence of two, or even more, primary malignancies that were diagnosed simultaneously, or within six months from each other. Studies have shown that the incidence of synchronous colon and breast cancer in women is only 3.85%, however data is limited in the male population.1 In the Philippines, this is the first reported case of synchronous colon and breast cancer in a male patient.Methods/Interventions: The patient is a 64-year-old male who had a 5-month history of intermittent abdominal pain and unintentional weight loss. Abdominal exam was essentially normal, with no palpable mass. On further examination, it was noted that he also had a 2-year history of a 4 x 4 cm firm right breast mass with peau d’orange. Colonoscopy showed an obstructing proximal ascending colon mass, of which biopsy was an adenocarcinoma. Gene testing revealed the following: proficient MMR, MSI high, no BRAF mutation, KRAS wild-type, and NRAS wild-type. Core needle biopsy of the right breast mass was an invasive carcinoma that was estrogen receptor/progesterone receptor-positive (ER/PR+) and HER2/neu-negative. PET-CT scan showed a hypermetabolic circumferential thickening at the ascending colon involving the ileocecal junction, and a hypermetabolic mass at the right breast. High FDG uptake in the following areas were suggestive of disseminated disease: lungs, peritoneum, hilar nodes, pelvic nodes, left pubic ramus, and left iliac bone.Results/Outcomes: In the multidisciplinary team (MDT) meeting done, it was decided to give the patient palliative chemotherapy regimen of 5-fluorouracil (5-FU), leucovorin, oxaliplatin (FOLFOX), and bevacizumab due to his poor functional status. Since he noted decreasing stool caliber, a proximal bowel diversion in the form of a loop ileostomy was planned to prevent any emergent need for abdominal surgery during chemotherapy. On follow-up, the patient reported tolerance to full diet with semi-formed output per stoma. He has since been started on the agreed palliative regimen.Conclusion/

Discussion: The presence of multiple primary cancers, family history of cancer, and cancer at an early age are factors indicative of a possible hereditary cancer syndrome (i.e., Lynch syndrome, etc.). The relationship of colon cancer to breast cancer, within or beyond these syndromes, has not yet been completely described in studies.2 Our patient had no risk factors for cancer nor did he fulfill any criteria for any syndrome. Thus, it is likely that this is a case of sporadic synchronous colon and breast cancer.

The sequence of management for multiple primary cancers often requires an MDT approach. Based on the gene testing results, the patient was started on FOLFOX with bevacizumab which is a first-line therapy in metastatic colon cancer, particularly given to KRAS wild-type/BRAF wild-type patients.3 While FOLFOX is not widely-used in treating breast cancers, 5-FU is a known effective agent used in combination with cyclophosphamide and methotrexate against metastatic breast cancer.4 A case report has also reported efficacy of FOLFOX in a woman with locally advanced colon cancer and recurrent breast cancer.5 Men with ER/PR+ breast cancers also benefit from sequential endocrine therapy such as tamoxifen or letrozole. Thus, since our patient had a hormone responsive metastatic breast cancer, hormonal therapy may be done following completion of palliative chemotherapy. Indeed, an MDT is crucial in the care of multiple primary cancers due to their rarity and complexity."Figure 1. CT scan cuts showing the lesions in the ascending colon (A), right breast (B), and lungs (C). PGH, 2023.


Figure 2. PET-CT scan demonstrating intense F-fluorodeoxyglucose uptake in lesions at the ascending colon (A) and right breast (B).PGH, 2023.
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