Cancer Diagnosis, Staging, and Treatment
Domain 2 - Cancer Diagnosis, Staging, and Treatment
This domain tests how you translate pathology, imaging, and clinical notes into ICD-O-3 codes, a stage, and a first-course treatment summary.
Core rules
- ICD-O-3 topography describes site; morphology describes histology and behavior. Code the most specific histology supported by the report; ambiguous wording such as 'consistent with' generally does not confirm a diagnosis.
- Staging: AJCC TNM, current edition, is the primary staging system; summary stage is a broader public-health measure. Use clinical stage before treatment and pathologic stage when resection occurs. Do not restage after progression.
- T, N, M: T reflects primary tumor size or invasion; N reflects regional nodes; M reflects distant metastasis. Stage grouping combines them.
- First course of treatment includes planned or delivered treatment before progression or recurrence, across surgery, radiation, and systemic therapy (chemotherapy, immunotherapy, hormone, targeted).
- Grade and biomarkers such as ER, PR, HER2, and Gleason score are site-specific factors that affect prognosis and treatment.
Worked example
A sigmoid colectomy specimen shows tumor through muscularis propria into pericolorectal fat, 2 of 14 nodes positive, and no metastases. T3 is invasion through muscularis propria into pericolorectal tissues; N1b is 2–3 positive regional nodes; M0. AJCC 8th edition grouping gives Stage IIIB. The registrar records pathologic stage, not clinical stage, and treats adjuvant chemotherapy as part of first course rather than a separate primary treatment event.
Traps
- Assigning pathologic stage when no resection occurred.
- Recording only post-neoadjuvant findings without recognizing the y-prefix context.
- Counting a biopsy as definitive surgery.
- Coding 'history of' treatment as active first course.