By Dr. Zoya Ahmed
Abstract:
Introduction:
Anal canal squamous cell carcinoma (SCC) is a
rare malignancy, accounting for approximately 2–4% of all
gastrointestinal cancers globally. In Pakistan, epidemiological
data remain sparse, and regional treatment outcomes are
underreported. Concurrent chemoradiotherapy (CCRT) is the
standard of care for non-metastatic disease, offering organ
preservation and curative potential. Factors such as HPV status
may influence response, yet their predictive value in South
Asian populations remains unclear.
Objective:
To evaluate early radiological response to
concurrent chemoradiotherapy (CCRT) in patients with anal
canal squamous cell carcinoma, and to explore the association
of HPV status and induction chemotherapy with this outcome.
Methodology:
A retrospective analysis was conducted on 35
patients diagnosed with anal canal SCC between January 2023
and June 2025. All patients received CCRT using either
intensity-modulated radiotherapy (IMRT) or volumetric
modulated arc therapy (VMAT). Radiotherapy doses ranged
from 50 Gy to 54 Gy, adjusted according to tumor size and
nodal involvement. Induction chemotherapy was administered
to 25 patients, while 10 patients did not receive it due to
contraindications. Chemotherapy regimens included
Mitomycin-C combined with Capecitabine or 5-FU, XELOX,
Cisplatin/5-FU and Cape/Mitomycin. HPV status was
documented for all patients. Radiological response was
evaluated three months post-treatment using RECIST criteria.
Results:
Among the 35 patients, complete response (CR) was
observed in 5 patients (15%), partial response (PR) in 21
(60%), stable disease (SD) in 5 (15%), and progressive disease
(PD) in 4 (10%). Among HPV-positive patients (n=22), CR
was observed in 5 (22.7%), PR in 14 (63.6%), SD in 2 (9.1%), and progression in 1 (4.5%). In HPV-negative patients (n=8),
CR occurred in 1 (12.5%), PR in 4 (50%), SD in 2 (25%), and
PD in 1 (12.5%). Patients with unknown HPV status
demonstrated favorable outcomes, with CR in 1(20%), PR in
3(60%), and SD in 1(20%). Chemotherapy omission was
associated with reduced response rates and increased
progression. Patients receiving Mitomycin-C and Capecitabine
showed the most favorable outcomes.
Conclusion:
This analysis underscores the prognostic
significance of HPV status and the inclusion of chemotherapy
in predicting early treatment response in anal canal squamous
cell carcinoma (SCC), particularly within resource-limited
settings. The omission of chemotherapy correlated with poorer
outcomes. HPV positivity emerged as a potential biomarker for
favorable response, suggesting its utility in stratifying
treatment intensity. Further prospective studies are needed to
validate these findings and guide treatment stratification.