Abstract
- Rectal cancer during pregnancy represents a clinical paradox in which the instinct to protect new life directly intersects with the urgency to preserve another. With an incidence of approximately 1 in 13,000 pregnancies, this rare condition challenges not only clinical decision-making but also the ethical and emotional dimensions of contemporary medical care. A 32-year-old primigravida at 26 weeks of gestation presented with rectal bleeding and was diagnosed with stage T4bN+M0 rectal adenocarcinoma. Despite the conventional recommendation of pregnancy termination in such circumstances, the patient expressed a strong desire to continue the pregnancy. A multidisciplinary team comprising colorectal surgeons, medical oncologists, radiation oncologists, and maternal-fetal medicine specialists developed a unified and coordinated treatment plan. The patient received neoadjuvant CAPOX (capecitabine [Xeloda] and oxaliplatin) chemotherapy during pregnancy, underwent cesarean delivery at 36 weeks of gestation, and subsequently completed postpartum chemoradiotherapy followed by curative laparoscopic oncologic resection. The child was delivered healthy, and the mother remained disease-free at a 5-year follow-up. This case demonstrates that life-threatening malignancy and ongoing pregnancy can coexist without compromise. Through carefully timed interventions, close cross-specialty collaboration, and respect for patient autonomy, both maternal and fetal outcomes were excellent. Within the evolving landscape of personalized cancer care, this case challenges outdated paradigms and reframes pregnancy not as a contraindication, but as a clinical variable that can be managed with precision and compassion. In addition to this illustrative case, we provide a focused review of the current literature to guide clinicians navigating this rare and complex clinical scenario.
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Keywords: Rectal neoplasms; Pregnancy; Multidisciplinary management; Neoadjuvant therapy; Fetal outcomes
INTRODUCTION
Colorectal cancer (CRC) during pregnancy is an exceptionally rare and clinically challenging scenario, with an estimated incidence of approximately 1 in 13,000 pregnancies [1]. The coexistence of a life-threatening malignancy alongside an ongoing pregnancy creates unique diagnostic and therapeutic dilemmas. Diagnosis is frequently delayed because presenting symptoms, such as abdominal pain, rectal bleeding, and anemia, overlap substantially with common features of normal pregnancy. Moreover, pregnancy-related physiological changes may obscure, mimic, or mask signs of underlying malignancy [2].
Managing CRC in pregnancy requires a delicate balance between optimizing maternal oncologic outcomes and ensuring fetal well-being. Treatment decisions are influenced by tumor stage, gestational age at diagnosis, and the patient’s preferences regarding continuation of pregnancy [2,3]. Available therapeutic options may include surgery, chemotherapy, and, in select cases, radiation therapy, all of which require precise timing to align oncologic priorities with obstetric considerations [4].
This case report underscores the critical role of a multidisciplinary team in coordinating neoadjuvant therapy, delivery planning, and definitive surgical management, while simultaneously ensuring appropriate fetal monitoring and safe childbirth. Such collaborative care is essential to achieving optimal outcomes for both mother and child.
CASE PRESENTATION
A 32-year-old primigravida at 26 weeks of gestation presented to a local hospital in February 2020 with a 1-month history of altered bowel habits accompanied by bloody, mucous stool. Her antenatal course had been uneventful until that time. Digital rectal examination revealed a non-fixed mass palpable on the anterior aspect of the mid rectum, while the uterine fundus was noted just above the umbilicus. Colonoscopy demonstrated a hemi-circumferential, nonobstructing mass located 8 cm from the anal verge (Fig. 1). Histopathological analysis confirmed moderately differentiated adenocarcinoma with focal mucinous features.
Given the patient’s strong desire to continue the pregnancy and her preference to avoid termination, she was referred to our center for multidisciplinary evaluation and coordinated management aimed at optimizing outcomes for both mother and fetus. At our institution, further diagnostic workup was undertaken. The carcinoembryonic antigen (CEA) level was 2.0 ng/mL. Following multidisciplinary review with a radiologist, pelvic magnetic resonance imaging (MRI) demonstrated a 5.3×4.5×5.1-cm lesion with heterogeneous signal intensity, consistent with mucin-producing adenocarcinoma. The tumor exhibited deep invasion into the mesorectal fat, involvement of the circumferential resection margin on the right side, and invasion of the posterior vaginal wall. No evidence of extramural venous invasion was identified (Fig. 2), and no hepatic metastases were detected. Chest computed tomography (CT) revealed no evidence of intrathoracic metastatic disease. Based on these findings, the patient was diagnosed with clinical stage T4bN+M0 rectal adenocarcinoma.
Following multidisciplinary team discussion, delivery after 34 weeks of gestation was recommended to optimize fetal outcomes. After thorough counseling regarding the proposed treatment strategy, including potential maternal and fetal risks such as intrauterine growth restriction and preterm labor, a shared decision was made to initiate neoadjuvant chemotherapy using the CAPOX (capecitabine [Xeloda] and oxaliplatin; capecitabine 1,000 mg/m² twice daily on days 1–14 and oxaliplatin 130 mg/m² administered intravenously on day 1) regimen (pregnancy category D). The patient received 3 cycles of chemotherapy, which were discontinued 3 weeks prior to the anticipated delivery. Throughout treatment, she was closely monitored by the maternal-fetal medicine team, with monthly assessments that included fetal growth surveillance and maternal health evaluation. No maternal or fetal complications were observed during this period.
To promote fetal lung maturity, the patient received intramuscular dexamethasone at a dose of 6 mg every 12 hours for 4 doses 1 week prior to delivery. Cesarean section was performed at 36 weeks of gestation without complications. The patient subsequently underwent neoadjuvant chemoradiotherapy consisting of 50.4 Gy delivered in 28 fractions with concurrent capecitabine. This approach was selected to achieve adequate local disease control given the clinical T4b staging, while simultaneously allowing sufficient time for uterine involution to facilitate safer and more effective definitive oncologic resection. Restaging pelvic MRI performed 8 weeks after completion of chemoradiotherapy demonstrated tumor size reduction to approximately 3 cm; however, persistent invasion into the mesorectal fat and continued contact with the anterior peritoneal reflection and posterior vaginal wall remained evident. Concurrent follow-up CT scans of the chest and abdomen revealed no distant metastases. The patient subsequently underwent laparoscopic low anterior resection with en bloc resection of the posterior vaginal wall and creation of a diverting loop ileostomy. Histopathological examination confirmed moderately differentiated adenocarcinoma with focal mucinous features and lymphovascular invasion. All resection margins were negative, and no malignancy was identified in the apical or perirectal lymph nodes, corresponding to ypT3N0M0 staging. The surgical specimen is shown in Fig. 3. Adjuvant chemotherapy with capecitabine was completed in 2020, followed by successful ileostomy closure. A summary of the treatment timeline is provided in Fig. 4.
At a 5-year follow-up in 2025, the patient remained disease-free, with a CEA level of 1.67 ng/mL. Surveillance CT imaging and colonoscopy demonstrated no evidence of local recurrence or distant metastasis. The child exhibited normal developmental milestones and age-appropriate cognitive function, with a pediatric assessment confirming a normal IQ (intelligence quotient). The child had successfully commenced primary school.
Ethics statement
Written informed consent was obtained from the patient for publication of the research details and clinical images. The requirement for ethics approval was waived by the Institutional Review Board of King Chulalongkorn Memorial Hospital, Faculty of Medicine, Chulalongkorn University.
REVIEW OF LITERATURE
In cases of CRC during pregnancy, the median age at diagnosis is 32 years (range, 17–46 years), with approximately 12% of cases diagnosed in the first trimester, 41% in the second trimester, and 47% in the third trimester [4]. Nearly half of affected patients present with stage IV disease, a presentation that is associated with significantly poorer maternal outcomes [5]. Accordingly, a high index of suspicion is essential, particularly in pregnant women with a personal or family history of colorectal polyps or cancer, unexplained weight loss, changes in bowel habits, rectal bleeding (the most common presenting symptom), or persistent abdominal pain [2].
Optimal management of CRC during pregnancy requires careful selection of diagnostic modalities that appropriately balance maternal benefit with fetal safety. CEA is not considered a reliable biomarker in this setting, as it demonstrates low sensitivity and specificity, and serum levels typically remain within normal limits or are only mildly elevated during pregnancy [6]. Lower gastrointestinal endoscopy is generally regarded as safe across all trimesters, although some guidelines recommend preferential performance during the second trimester when feasible. Nevertheless, deferring endoscopy may delay diagnosis and initiation of treatment, which may ultimately pose greater risks to both maternal and fetal outcomes than the procedure itself [7].
For bowel preparation, polyethylene glycol is preferred over sodium phosphate because of its minimal systemic absorption, reduced abdominal bloating, and lower risk of adverse events, including acute phosphate nephropathy and electrolyte disturbances [8]. Fetal monitoring should be integrated into the endoscopic protocol. In pregnancies under 24 weeks of gestation, Doppler ultrasonography should be used to confirm fetal heart activity both before and after the procedure. For pregnancies beyond 24 weeks of gestation, continuous electronic monitoring of fetal heart rate and uterine contractions is recommended [9].
IMAGING MODALITIES
In nonpregnant patients, staging for CRC typically includes CT of the chest and abdomen, along with pelvic MRI. In pregnant patients, however, the use of these imaging modalities requires careful consideration, particularly during the period of organogenesis (gestational weeks 2–8), when the fetus is most susceptible to the teratogenic effects of ionizing radiation. Recommended fetal radiation exposure thresholds are ≤0.05 Gy during the first trimester and ≤0.5 Gy during the second and third trimesters [10].
CT of the chest delivers an estimated fetal radiation dose of less than 0.001 Gy and is therefore considered safe throughout all stages of pregnancy. In contrast, CT of the abdomen results in higher fetal radiation exposure, ranging from approximately 0.01 to 0.05 Gy, and should generally be avoided during the first trimester, with its use reserved for carefully selected cases thereafter [11]. MRI of the abdomen and pelvis offers a radiation-free alternative and is generally regarded as safe during pregnancy. However, the use of gadolinium-based contrast agents remains controversial. Although current evidence does not demonstrate a significant increase in fetal or neonatal mortality, concerns persist because of the fetus’s immature renal clearance and underdeveloped blood-brain barrier, which may increase the risk of gadolinium deposition. Consequently, most clinical guidelines recommend that gadolinium contrast be used during pregnancy only when its potential diagnostic benefit clearly outweighs the associated risks.
TREATMENT MODALITIES
Surgical intervention
Due to the rarity of CRC during pregnancy, no consensus guidelines currently exist, and management decisions must therefore be individualized. Multidisciplinary involvement is essential to support informed, balanced, and ethically sound decision-making. Surgical intervention is generally considered safe across all trimesters of pregnancy, although the second trimester is associated with lower risks of miscarriage and preterm labor [2]. Regardless of gestational age, oncologic surgery should not be delayed when clinically indicated. A clearly defined surgical plan, including perioperative fetal monitoring, is recommended to ensure fetal safety during operative procedures. Although minimally invasive surgery has been reported in pregnant patients, open surgery remains the most established standard of care in this setting [12,13].
Fetal viability represents a key consideration in multidisciplinary treatment planning. With advances in neonatal care, fetal viability is generally recognized at 24 weeks’ gestation. Between 24 and 34 weeks, antenatal corticosteroids, such as dexamethasone, are recommended to promote fetal lung maturity. Late preterm deliveries occurring between 34 and 36 weeks are associated with relatively low complication rates, whereas delivery at or beyond 37 weeks is ideal and should be planned when feasible. When earlier intervention is required, local legal frameworks governing abortion must be considered, as these regulations may influence treatment timelines [3]. Nevertheless, maternal autonomy must be respected, and patients should be supported in making informed decisions, including the option of pregnancy termination when medically appropriate.
Systemic therapy and radiotherapy
Systemic chemotherapy for CRC during pregnancy primarily involves fluoropyrimidines, including 5-fluorouracil (5-FU) and capecitabine. These agents, classified as pregnancy category D, may be administered during the second and third trimesters, when organogenesis has been completed [14]. Their use during the first trimester is contraindicated because of the increased risk of congenital anomalies, including microcephaly, low-set ears, ventriculomegaly, and skeletal abnormalities. Prior to treatment initiation, assessment of dihydropyrimidine dehydrogenase (DPD) activity is recommended, as DPD deficiency may result in severe or life-threatening toxicity. Although data on oxaliplatin and irinotecan use during pregnancy remain limited, oxaliplatin, commonly used in combination regimens such as FOLFOX (5-FU, leucovorin, and oxaliplatin) or CAPOX in the general population, may be cautiously considered during the second and third trimesters. Such decisions should be based on thorough multidisciplinary evaluation and shared decision-making with the patient, balancing oncologic benefit against potential fetal risk.
Targeted therapies, including anti–vascular endothelial growth factor and anti–epidermal growth factor receptor agents, are contraindicated during pregnancy. These agents disrupt angiogenesis and may adversely affect placental and uterine vascular development, thereby posing significant risks to fetal growth and viability.
Radiotherapy, which is commonly administered at doses between 45 and 50 Gy for rectal cancer, results in substantially higher radiation exposure than diagnostic imaging and carries a high risk of teratogenic effects. Consequently, radiotherapy is contraindicated throughout all trimesters of pregnancy. In patients for whom radiotherapy is clinically indicated, such as those with locally advanced rectal cancer, treatment should be deferred until after delivery whenever feasible.
Mode of delivery
Vaginal delivery is feasible in approximately 60% of CRC cases during pregnancy, particularly among patients with colon cancer. In cases of rectal cancer, however, cesarean section is often preferred, especially when the tumor is located anteriorly or in the lower rectum, due to concerns regarding hemorrhage, tumor disruption, or obstruction of the birth canal. When definitive colorectal surgery is planned postpartum, a delay of 2 to 4 weeks is recommended to allow for uterine involution and reduction in pelvic vascularity, thereby minimizing surgical risk [6].
The patient described in this report illustrates that pregnancy termination is not invariably required in the management of CRC during pregnancy. Careful evaluation of each treatment modality, including its risks, benefits, and optimal timing, is essential. In this case, the patient successfully underwent neoadjuvant chemotherapy during pregnancy, followed by postpartum concurrent chemoradiotherapy, laparoscopic low anterior resection with en bloc vaginal resection, and subsequent adjuvant chemotherapy. Long-term follow-up demonstrated favorable outcomes for both mother and child, with no treatment-related complications observed.
CONCLUSION
CRC during pregnancy presents substantial diagnostic and therapeutic challenges, as its clinical manifestations often overlap with common pregnancy-related symptoms. Maintaining a high index of clinical suspicion is therefore critical to achieving timely diagnosis. Optimal management requires an individualized, multidisciplinary approach that carefully balances maternal oncologic priorities with fetal considerations. Informed consent remains a central component of patient-centered care, facilitating collaborative decision-making and supporting the pursuit of the best possible outcomes for both mother and child.
ARTICLE INFORMATION
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Conflict of interest
No potential conflict of interest relevant to this article was reported.
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Funding
None.
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Author contributions
Conceptualization: all authors; Investigation: SM; Methodology: SJ; Resources: SM; Supervision: SM; Writing–original draft: SJ; Writing–review & editing: all authors. All authors read and approved the final manuscript.
Fig. 1.Endoscopic findings. (A) Showing a hemi-circumferential rectal mass. (B) The lesion is located approximately 8 cm from the anal verge.
Fig. 2.The rectal magnetic resonance imaging at the time of diagnosis. (A) The axial view, showing the extension of the tumor into the mesorectal fat and its abutment to the posterior wall of the vagina (arrow). (B) The sagittal view.
Fig. 3.The specimen after low anterior resection. The yellow arrow highlights the posterior wall of the vagina, while the white arrow indicates the location of the tumor.
Fig. 4.The treatment timeline. GA, gestational age; CAPOX, capecitabine (Xeloda) and oxaliplatin; MFM, maternal-fetal medicine; CCRT, concurrent chemoradiotherapy; LAR, low anterior resection; DLI, diverting loop ileostomy.
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