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

Abstract

Introduction: 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.

Case presentation: 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.

Conclusions: 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.

Keywords: case report; colorectal cancer; neoadjuvant chemotherapy; pregnancy; second trimester.

Fig. 1. Pretreatment examination findings. (A) Sigmoidoscopy images revealing a semicircular type 2 tumor in the rectum above the peritoneal reflection. A biopsy confirmed a diagnosis of adenocarcinoma (group 5). (B) Enhanced computed tomography showing thickening of the rectal wall above the peritoneal reflection (arrowheads), with no evidence of invasion into surrounding tissues, lymph node metastasis, or distant metastasis.

Fig. 2. Neoadjuvant chemotherapy and post-delivery findings. (A) Colonoscopy images demonstrating shrinkage of the primary tumor compared to pretreatment findings. (B) Computed tomography confirming reduction in the size of the primary tumor (arrowheads), with no new lesions identified. (C) Barium enema revealing an irregularly elevated lesion with wall deformity in the upper rectum (arrow). (D) Contrast-enhanced magnetic resonance imaging indicating partial rupture and irregularity of the low-intensity muscularis propria (arrow), suggesting a T3 invasion depth.

Fig. 3. Intraoperative findings. Robot-assisted low anterior resection of the rectum with D3 lymph node dissection was performed. The uterus had contracted postpartum, allowing standard rectal cancer surgery. However, during pelvic manipulation, lifting of the uterus caused a tear due to its puerperal state (dotted circle), which was repaired by an obstetrician-gynecologist via suturing.

Fig. 4. Surgical specimen and loupe image. (A and B) Gross specimens from low anterior resection of the rectum (the right side represents the oral side, the left side is the anal side, the top is the dorsal side, and the bottom is the ventral side), with gross appearance presented in (B). The areas surrounded by red lines indicate the location of the cancer. (C) Loupe image of hematoxylin and eosin staining. The postoperative diagnosis was ypT2N0M0, stage I.