# Neoadjuvant Chemotherapy for Stage II Rectal Cancer Diagnosed in the Second Trimester of Pregnancy: A Case Report

## TL;DR

A pregnant woman with stage II rectal cancer received chemotherapy during her second trimester, delivered a healthy baby, and later underwent successful surgery.

## Contribution

This case report presents a successful treatment strategy using neoadjuvant chemotherapy for rectal cancer during pregnancy.

## Key findings

- Neoadjuvant chemotherapy was safely administered during the second trimester without adverse effects on the fetus.
- The patient delivered a healthy baby at 35 weeks and later underwent successful rectal cancer surgery.
- Post-surgery pathology showed a favorable response to chemotherapy with ypStage I cancer.

## Abstract

The onset of colorectal cancer during pregnancy is rare, and no standard treatment has been established. In this report, we present the case of a woman with clinical stage II rectal cancer diagnosed in the second trimester, in which neoadjuvant chemotherapy was administered, followed by delivery once fetal development was sufficiently advanced, and surgery was performed afterward.

The patient was a 36-year-old woman at 22 weeks of gestation. Sigmoidoscopy was performed for hematochezia, which revealed a semicircular type 2 tumor in the rectum. A biopsy confirmed the presence of adenocarcinoma. A thorough systemic examination revealed no lymph nodes or distant metastases. After discussing the risks and benefits with the patient, her family, a pediatrician, and an obstetrician, we decided to administer neoadjuvant chemotherapy. The plan was to deliver the fetus after it had adequately developed and then perform radical surgery for rectal cancer after delivery. Neoadjuvant chemotherapy comprised 4 courses of the modified FOLFOX6 regimen, including leucovorin calcium (folinic acid), fluorouracil, and oxaliplatin. The patient had a vaginal delivery at 35 weeks and 5 days of gestation, 23 days after the last chemotherapy dose. The newborn was healthy with no congenital anomalies. On the 27th day after delivery, a robot-assisted low anterior resection of the rectum was performed. The pathological findings revealed rectal cancer located above the peritoneal reflection, ypT2N0M0, and ypStage I. The patient recovered well and was discharged 12 days after surgery. At the time of writing, both the mother and child are doing well, with no evidence of recurrence 6 months after surgery.

In cases of colorectal cancer during pregnancy, it is important to select a treatment plan that considers the site and stage of the tumor, number of weeks of pregnancy, and conditions of the fetus and mother. Even in cases of clinical stage II colorectal cancer diagnosed during the second trimester, where immediate surgery is not feasible, neoadjuvant chemotherapy can be considered a viable treatment option.