FIGO Staging of Ovarian Cancer with Sigmoid Colon Involvement
Ovarian cancer with sigmoid colon involvement is classified as FIGO stage IIIC according to the International Federation of Gynecology and Obstetrics (FIGO) staging system.
Understanding FIGO Stage IIIC Classification
According to the FIGO staging system, stage IIIC is defined as:
- Tumor involving one or both ovaries with peritoneal metastasis beyond the pelvis >2 cm in greatest dimension and/or metastasis to the retroperitoneal lymph nodes 1
- This includes extension of tumor to the capsule of liver and spleen without parenchymal involvement of either organ 1
Sigmoid colon involvement is specifically considered part of stage IIIC disease because:
- It represents peritoneal metastasis beyond the pelvis
- The involvement typically exceeds 2 cm in greatest dimension
- It does not meet criteria for stage IV disease unless there is transmural invasion with mucosal involvement 2
Important Distinctions
It's crucial to understand that:
Not Stage II: While sigmoid colon is anatomically in the pelvis, involvement is not classified as stage II disease. Stage II is limited to extension to other pelvic tissues without spread beyond the pelvis 1
Not Stage IV: Sigmoid colon involvement is only considered stage IV (specifically IVB) if there is transmural bowel infiltration with mucosal involvement 2. Otherwise, it remains stage IIIC.
Depth of invasion matters: Research has shown that depth of recto-sigmoid colon wall invasion does not have prognostic significance that would justify automatic assignment to stage IV 3
Staging Process Requirements
Proper staging requires:
- Comprehensive surgical exploration via laparotomy
- Careful examination of the entire abdominal cavity
- Collection of peritoneal washings
- Multiple biopsies of peritoneal surfaces
- Assessment of lymph nodes 1
Clinical Implications
This staging has important treatment implications:
- Primary debulking surgery with the goal of complete cytoreduction is the cornerstone of treatment
- Includes total abdominal hysterectomy, bilateral salpingo-oophorectomy, omentectomy, and resection of all visible disease including sigmoid colon involvement when necessary 4
- Followed by platinum-based chemotherapy, typically carboplatin plus paclitaxel for 6 cycles 4
Common Pitfalls in Staging
- Failing to distinguish between serosal/subserosal invasion versus transmural invasion with mucosal involvement
- Incorrectly classifying sigmoid colon involvement as stage II or automatically as stage IV
- Not performing adequate surgical exploration to properly assess the extent of disease
The 2014 revised FIGO staging system provides more precise subcategorization of stage III disease, which helps guide appropriate treatment decisions and provides more accurate prognostic information 2.