Coding "None" vs. "Unknown" in the Collaborative Staging System, TNM, & Summary Stage
In the process of bringing together the principles of Summary Stage, TNM Categories and Stage Groupings, and SEER Extent of Disease coding, the Collaborative Staging System has also attempted to update abstracting rules to deal with the contemporary health care environment, in which the completeness of staging documentation in the medical record has become an issue. In many circumstances, a patient's insurance will not pay for an imaging study or lab test that is expected to be negative but may otherwise be considered part of an 'ideal' cancer staging workup. Similarly, the content of a clinician's notes has changed over time to simply report any symptomatic, suspicious, or involved areas rather than chronicle every body part that is normal. This change in documentation is a source of frustration to data collectors who rely on statements of normalcy or negativity to establish the boundaries of how far the cancer has spread.
When clinical practice changes and data collection guidelines do not, the completeness of the data is affected. The implementation of the Collaborative Staging System introduces a paradigm shift in the collection of information documenting the extent of disease, particularly in the collection of information about regional lymph nodes or distant metastases for primary sites not easily examined by palpation, observation, physical examination, or other clinical methods. These 'inaccessible' primary sites include bladder, kidney, prostate, esophagus, stomach, lung, liver, corpus uteri and ovary.
The Collaborative Staging System allows data collectors to record regional lymph nodes as negative rather than unknown (based on clinical evaluation) when there is no mention of regional lymph node involvement in the physical examination, pre-treatment diagnostic testing or surgical exploration, and the patient receives what would be usual treatment to the primary site (treatment appropriate to the stage of disease as determined by the physician). The basis for this shift in the approach to information missing from the medical record is that typically the clinician reports positive findings and tends to remain silent on some or all negative findings. This new coding guideline also allows data collectors to record distant metastasis clinically as none rather than unknown (again, based on clinical evaluation) when the clinician proceeds with usual treatment of the primary site, since this action presumes the absence of distant metastasis that would otherwise change the treatment approach.
These guidelines apply primarily to localized or early (T1, T2) stage in the TNM system for inaccessible primary sites. The code(s) for unknown information can and should be used in situations where there is reasonable doubt that the tumor is no longer localized. An example would be when there is clinical evidence that a prostate cancer has penetrated through the capsule into the surrounding tissues (regional direct extension/T3a) and regional lymph node involvement is not mentioned.
For primary sites that can be observed, palpated or examined without instruments, such as breast, oral cavity, skin, salivary gland, thyroid, and other organs, there should be some description of the regional lymph nodes. A statement such as "remainder of examination negative" is sufficient to code regional lymph nodes as clinically negative.
By coding regional lymph nodes as negative and/or coding distant metastasis as none rather than coding these fields as unknown, the Collaborative Staging System computer algorithms will be able to derive a stage group that includes the best information.
In summary, the developers of the CS model believe that it will improve the quality of data being collected by the cancer registry community. Uniform rules and standardized training will make it easier for cancer registry personnel to complete staging tasks.