Repeated local recurrence of rectal mucinous adenocarcinoma in a young adult after multiple chemotherapy courses: a case report

Abstract

Colorectal cancer (CRC) is the fourth most common cancer and the fifth leading cause of cancer-related mortality in Indonesia. An increasing incidence of CRC among young patients has been highlighted in several studies. Most reports showed that young patients with CRC were associated with specific clinicopathological characteristics, including more advanced tumor stage, poor histologic features, more mucinous tumors, high recurrence events, and poor responses to standard therapy. A 29-year-old woman presented with a lump in the anal region, hematochezia, and weight loss over two months. Histopathological examination after laparotomy and tumor resection revealed a moderately differentiated mucinous adenocarcinoma of the rectum, stage
pT3N1cM0 (IIIB). She had received eight cycles of first-line chemotherapy with Capecitabine monotherapy, then second-line chemotherapy with the FOLFOX regimen for eight cycles, followed by concurrent chemoradiotherapy (CCRT) with Capecitabine, and finally eight cycles of third-line chemotherapy with the
XELIRI regimen due to a residual rectosigmoid mass. Post-treatment evaluation showed she was asymptomatic, and an abdominal MSCT scan revealed no residual mass, indicating a complete clinical response. However, ten months later, she experienced recurrent symptoms, including hematochezia and a lump in the anal region. Biopsy of the lesion confirmed mucinous adenocarcinoma of the anorectum with clinical stage rT4bN1aM0 (IIIC). The mucinous subtype of adenocarcinoma is more common in younger patients and is generally
considered a poor prognostic factor. The limited response to therapy has been linked to a relatively hypoxic tumor environment caused by decreased blood supply, which may diminish the effectiveness of chemotherapy. The mucous layer and abundant mucin may also hinder the delivery of chemotherapy agents
and reduce the penetration of radiation. Biological factors such as mutations in KRAS and BRAF, overexpression of the MUC2 gene, and increased MSI or DNA MMR deficiency have been observed in mucinous cancers, playing an important role in determining treatment options.