Cancer Stage for pT4a, pN1c
This patient has Stage IIIC anal cancer based on the AJCC 8th edition TNM staging system. 1
Staging Rationale
The stage classification is determined by combining the T and N categories according to the AJCC staging criteria for anal cancer:
T4a classification: Indicates a tumor of any size invading adjacent organs (excluding sphincter, rectal wall, perianal skin, and subcutaneous tissues) 1
N1c classification: Represents N1b (external iliac lymph node involvement) combined with any N1a nodes (inguinal, mesorectal, superior rectal, obturator, and/or internal iliac) 1
Stage grouping: According to AJCC 8th edition, T4 with N1 disease (any subcategory including N1c) and M0 is classified as Stage IIIC 1
Clinical Implications
This represents very advanced locoregional disease with significant prognostic implications:
The 5-year survival rate for Stage III anal cancer is approximately 40%, which is substantially lower than Stage I (80%) or Stage II (60%) disease 2
Lymph node involvement, particularly the N1c pattern with external iliac nodes, significantly worsens prognosis compared to node-negative disease 2
T4 disease indicates invasion of adjacent structures, placing this patient in a high-risk category requiring aggressive multimodality treatment 1
Treatment Approach
Standard treatment for Stage IIIC anal cancer consists of definitive concurrent chemoradiation therapy:
Primary treatment is chemoradiation with cisplatin-based chemotherapy or 5-FU plus mitomycin as radiosensitizers 1
Surgical resection is typically reserved for salvage therapy if there is residual or recurrent disease after chemoradiation 2
The radiation field must encompass all involved nodal basins, including the external iliac nodes given the N1c classification 1