What is ICD-O-3 topography and how does it differ from ICD-10-CM?

• A. ICD-O-3 topography codes designate tumor site.
• B. ICD-10-CM codes are clinical diagnoses used in medical records.
• C. ICD-O-3 morphology codes are used for treatment planning.
• D. Registries use ICD-O-3 for site and morphology.

Answer: (D)

The main idea is how ICD-O-3 is used specifically for cancer data collection versus how ICD-10-CM is used in general medical records. ICD-O-3 is designed for cancer registries and codes two things: where the cancer is located (topography, the tumor site) and what type of tumor it is (morphology, including histology and behavior). This structure lets registries systematically categorize cancers for epidemiology and surveillance.

The statement that registries use ICD-O-3 for site and morphology directly describes its purpose and how it differs from ICD-10-CM, which is the broader clinical diagnosis coding system used in medical records and billing. ICD-10-CM focuses on describing patient diagnoses in everyday clinical care, not the specialized site-and-histology coding scheme needed for cancer surveillance.

So, this answer best captures the role of ICD-O-3 in registries and how it differs in purpose from ICD-10-CM. The other options touch on parts of ICD-O-3 or ICD-10-CM, but they don’t explain the registry-focused use as clearly.