The extent or stage of cancer at the time of diagnosis is a key factor that defines prognosis and is a critical element in determining appropriate treatment based on the experience and outcomes of groups of previous patients with similar stage. In addition, cancer stage often is a key component of inclusion, exclusion, and stratification criteria for clinical trials. Indeed, accurate staging is necessary to evaluate the results of treatments and clinical trials, to facilitate the exchange and comparison of information across treatment centers and within and between cancer-specific registries, and to serve as a basis for clinical and translational cancer research. At the national and international levels, a cohesive approach to the classification of cancer provides a method of clearly conveying clinical experience to others without ambiguity.

The most clinically useful staging system is the tumor, node, and metastasis (TNM) staging system developed by the American Joint Committee on Cancer (AJCC) in collaboration with the Union for International Cancer Control (UICC), herein referred to as the AJCC TNM staging system. The AJCC TNM system classifies cancers by the size and extent of the primary tumor (T), involvement of regional lymph nodes (N), and the presence or absence of distant metastases (M), supplemented in recent years by evidence-based prognostic and predictive factors.

NOTE: The AJCC Manual for Staging Cancer, Third Edition is used with cases diagnosed from 1989-1992.   

The AJCC Manual for Staging Cancer, Fourth Edition, is used with cases diagnosed from 1993 to 1997.

The AJCC Cancer Staging Manual, Fifth Edition, is used with cases diagnosed from 1998 to 2002.

The AJCC Cancer Staging Manual, Sixth Edition, is used with cases diagnosed from 2003 to 2009.

The AJCC Cancer Staging Manual, Seventh Edition, is used with cases diagnosed 2010 to 2017.

The AJCC Cancer Staging Manual, Eighth Edition, is used with cases diagnosed 2018 forward

NOTE: For 2008 diagnoses forward, ACoS requires clinical TNM staging assigned by a physician if available.  If not available, these fields must be completed by the registrar.  Pathologic TNM is not required.  For pre-2008 diagnoses, physician-assigned TNM stage is required for both clinical and pathologic staging in approved programs. Physicians may choose to record both the clinical and the pathologic stage if applicable. Registrars are required to report both if information is available from the physician. KCR requires only one TNM stage-- pathologic if the information is available, otherwise clinical.

The TNM general rules applicable to all sites contained in the Eighth Edition are as follows:

  1. All cases should be confirmed microscopically for classification by TNM.  Cases that do not have any biopsy or cytology of the tumor can be staged, but survival should be analyzed separately.  These cases should not be included in overall disease survival analyses.  
  2. Eligible time period for determination of staging:  
  3. Clinical staging, designated cTNM, includes any information obtained about the extent of cancer before initiation of definitive treatment (surgery, systemic or radiation therapy, active surveillance, or palliative care) or within four months after the date of diagnosis, whichever is shorter, as long as the cancer has not clearly progressed during that time frame.  
  4. Pathologic staging, designated pTNM, includes any information obtained about the extent of cancer up through completion of definitive surgery as part of first course treatment or identified within four months after the date of diagnosis, whichever is longer, as long as there is no systemic or radiation therapy initiated or the cancer has not clearly progressed during that time frame. 
  5. Post-therapy staging, designated ypTNM. The time frame should be such that the post neoadjuvant surgery and staging occur within a time frame that accommodates disease-specific circumstances, as outlined in the specific chapters and in relevant guidelines.
    Note: Clinical stage should be assigned before the start of neoadjuvant therapy.
  6. In cases where there is documented progression of cancer prior to the initiation of therapy or surgery, only information obtained prior to documented progression is used for staging.  
  7. If uncertainty exists regarding how to assign a category, subcategory, or stage group, the lower of the two possible categories, subcategories, or groups is assigned for • T, N, or M • prognostic stage group/stage group Stage groups are for patient care and prognosis based on data. Physicians may need to make treatment decisions if staging information is uncertain or unclear.
    Note: Unknown or missing information for T, N, M or stage group is never assigned the lower category, subcategory, or group.

  8. If information is not available to the cancer registrar for documentation of a subcategory, the main (umbrella) category should be assigned (e.g., T1 for a breast cancer described as <2 cm in place of T1a, T1b, or T1c). If the specific information to assign the stage group is not available to the cancer registrar (including subcategories or missing prognostic factor categories), the stage group should not be assigned but should be documented as unknown.

  9. If a required prognostic factor category is unavailable, the category used to assign the stage group is: • X, or • If the prognostic factor is unavailable, default to assigning the anatomic stage using clinical judgment.

  10. The recommended histologic grading system for each disease site and/or cancer type, if applicable, is specified in each chapter and should be used by the pathologist to assign grade. The cancer registrar will document grade for a specific site according to the coding structure in the relevant disease site chapter.
  11. If multiple tumors of the same histology are present in one organ: • the tumor with the highest T category is classified and staged, and • the (m) suffix is used • An example of a preferred designation is: pT3(m) N0 M0. • If the number of synchronous tumors is important, an acceptable alternative designation is to specify the number of tumors. For example, pT3(4) N0 M0 indicates four synchronous primary tumors.
    Note: The (m) suffix applies to multiple invasive cancers. It is not applicable for multiple foci of in situ cancer or for a mixed invasive and in situ cancer.

  12. If there is no evidence of a primary tumor, or the site of the primary tumor is unknown, staging may be based on the clinical suspicion of the organ site of the primary tumor, with the tumor categorized as T0. The rules for staging cancers categorized as T0 are specified in the relevant disease site chapters.In the case of a primary of unknown origin, staging will be based on reasonable clinical certainty of the primary organ.

  13. If reasonable clinical certainty is not obvious, the case cannot be staged. For example, if a patient has brain metastases diagnosed by a computed tomographic (CT) imaging scan, and the physician records that the primary is probably lung, code the primary site to lung and use the lung classification system for staging. However, if a patient is noted to have metastatic disease to the liver, and the pathology report cites that the primary may be lung or colon, this case cannot be staged, unless the origin of the primary is documented elsewhere.

  14. For in-situ classification, if there is an acceptable histologic classification of in-situ carcinoma as determined by your pathologist, but it has not been specified in the AJCC chapter, it can be used to classify pTis.  The correct classification for in-situ lesions is pTis cN0 cM0, and should be reported as both clinical stage group 0 and pathologic stage group 0.
  15. If pathologic assessment of lymph nodes reveals negative nodes but the number of examined lymph nodes is less than the suggested number for lymph node dissection, classify the N category as pN0. Only one lymph node is required to be removed for pathologic staging.
  16. Isolated tumor cells (ITC's) are single tumor cells or small clusters of cells not more than 0.2 mm in greatest dimension that are usually detected by immunohistochemistry or molecular methods. Cases with ITC's in lymph nodes or at distant sites should be classified as N0 or M0, respectively. The same applies to cases with findings suggestive of tumor cells or their components by non morphologic techniques such as flow cytometry or DNA analysis. These cases should be analyzed separately and have special recording rules in the specific organ site.
  17. Except where pM is positive, cM should be used along with pT and pN for calculating pathologic stage; "pM0" is not a valid concept. "MX" is not a valid category from 2010 forward.  Infer status as cM0 unless known M1.  

When physician and registrar disagree on correct TNM stage:

In situations in which the registrar disagrees with the TNM stage assigned by the physician, the registrar should attempt to resolve the discrepancy with the appropriate physician. It is also recommended that hospitals with ACoS approved cancer programs have these discrepancies reviewed by the Cancer Committee liaison to the registry if further resolution is needed. The physician’s TNM classification and stage group should be recorded in the cancer registry database and the "staged by" field should indicate physician.  Any discussion or disagreement by the registrar and/or registry physician advisors should be recorded in text.  

Amin, Mahul B.; Gress, Donna M.; Meyer Vega, Laura R.; Edge, Stephen B.. AJCC Cancer Staging Manual, Eighth Edition (Page 22). American College of Surgeons. Kindle Edition.