EP1002 - Defining a Distinct Entity: Clinical Characteristics of Young Onset Rectal Cancer with Complete Response

ePoster Presenter(s)

• SG

  Shadin Ghabra, MD

  Resident
  Medstar Georgetown University Hospital
  Medstar Georgetown University Hospital
  Arlington, VA, United States

  Disclosure information not submitted.

  View ePoster

Author(s)

• 

  Jacob M. Broome, MD

  General Surgery Resident
  MedStar Georgetown-Washington Hospital Center
  Georgetown Washington Hospital Center
  Washington, DC, United States

  All disclosed relationships have been reviewed and managed prior to the start of this activity. Any relevant relationships will be listed below. This individual has no financial relationships to disclose
• 

  Jacob Neary, MS, MD

  Fellow
  MedStar Washington Hospital Center
  Medstar Washington Hospital Center-Georgetown University Hospital
  Washington, DC, United States

  Disclosure information not submitted.
• AH

  Alana Hagley, n/a

  PGY3 Surgery Resident
  Medstar Georgetown/Washington Hospital Center
  Washington, District of Columbia, United States

  Disclosure information not submitted.
• 

  Mariana Tumminello, MD

  Resident Physician
  Medstar Georgetown Washington Hospital Center
  MedStar Georgetown/Washington Hospital Center
  Washington, DC, United States

  All disclosed relationships have been reviewed and managed prior to the start of this activity. Any relevant relationships will be listed below. This individual has no financial relationships to disclose
• AF

  Anne Fabrizio, MD

  Colon and Rectal Surgeon
  Medstar Georgetown University Hospital
  Washington, District of Columbia, United States

  Disclosure information not submitted.
• ZS

  Zhifei (Jeff) Sun, MD

  Assistant Professor of Surgery
  MedStar Health
  Washington, District of Columbia, United States

  Disclosure information not submitted.
• 

  Preetha Ali, MD

  Assistant Professor of Surgery
  MedStar Health
  Washington, District of Columbia, United States

  Disclosure information not submitted.
• SB

  Sara Berkey, MD

  Assistant Professor of Surgery
  MedStar Health
  Washington, District of Columbia, United States

  All disclosed relationships have been reviewed and managed prior to the start of this activity. Any relevant relationships will be listed below. This individual has no financial relationships to disclose

Senior Author(s)

• BB

  Brian Bello, MD

  Regional Chief of Colorectal Surgery
  MedStar Health

  All disclosed relationships have been reviewed and managed prior to the start of this activity. Any relevant relationships will be listed below. This individual has no financial relationships to disclose

Purpose/Background: As young onset rectal cancer is on the rise, data on treatment response in this population remain limited. Our aim is to elucidate the relationship between different clinical factors and tumor characteristics of treatment response to neoadjuvant therapy in young onset rectal cancer.

Methods/Interventions: Data was collected retrospectively between 2015 and 2022 from the US Rectal Cancer Research Group for patients with stage II or stage III rectal cancer who underwent total neoadjuvant therapy (TNT) with organ preservation. Patients were divided into young onset rectal cancer (YORC) of < 50 years, and late onset rectal cancer (LORC) >50 years. We defined complete response as those who had a durable response with organ preservation at time of last contact. Patient demographics, tumor characteristics, MSI status, neoadjuvant therapy type, use of immunotherapy, and mortality were additionally compared between the two groups. The primary outcome was durable clinical complete response to neoadjuvant treatment. Univariate and multivariate analysis were performed using SPSS.

Results/Outcomes: Data included 685 patients with rectal cancer, of those, 110 (16.1%) were younger than 50 years. The median ages were 46 and 65 years in the YORC and LORC groups, respectively. Patents with YORC were associated with higher odds of durable clinical complete response (OR 5.092, 95% CI 2.59-9.97, p < 0.001), as was male gender (OR 6.56, 95% CI 4.46-1.04, p < 0.001). Additionally, race other than Caucasian or Black was associated with higher odds of complete therapeutic response (OR 0.06, 95% CI 0.04-0.09, p < 0.001). The BMI was similar in both groups (27.7% vs 28.1%, p = 0.812). Suspicious pelvic lymph nodes detected by imaging were more common in the YORC group compared to LORC (29.1% vs 27.3%, p < 0.001). Stage II and III were more seen in YORC compared to LORC (24.5% vs 20%, 75.5% and 55.7% respectively), however multivariant analysis did not reflect significance (OR 1.576, 95% CI 0.90-2.74, p =0.109). Moderately differentiated adenocarcinoma was the most common histological subgroup and was more common in the YORC (67.3%) group than in the LORC (50.4%,) group (OR 0.98, 95% CI 0.39-2.43, p = 0.96). MSI-high tumors were seen more commonly in YORC (2.7%) than LORC (1.6%) (OR 02.14 95% CI 0.47-9.97, p = 0.33). The neoadjuvant regimen of TNT LC-CRT consolidation and TNT LC-CRT induction was used more in patients with YORC compared to LORC (54.5% and 28.2% vs 28.9% and 24% respectively), however was not significantly associated with durable clinical complete response (OR 1.35, 95% CI 0.36-5.04, p = 0.66). This was similar for YORC TNT-SCRT (OR 0.75, 95% CI 0.31-1.84, p = 0.53). A durable clinical complete response was seen in 90.9% in the YORC group compared to 66.3% in LORC (p < 0.001). Mortality for LORC was higher (2.8% vs 0%, p < 0.001).

Conclusion/Discussion: Male gender and race were associated with higher odds of durable clinical complete response. Tumor stage, grade, and MSI status were not significantly associated with response outcomes. Limitations included a predominately male population and lack of long term follow up. This study provides insights that may improve the ability to anticipate treatment response in young onset rectal cancer.

Table 1.
Demographics and Tumor Characteristics of patients with Young Onset Rectal Cancer vs, Late Onset Rectal Cancer.