Staging

American Joint Committee on Cancer (AJCC) 8th Edition MCC Staging System Table:
·        MCC is divided into stages depending on the size of the primary tumour and extent of disease in the lymph nodes and elsewhere in the body (metastasis). The stage at diagnosis is the major determinant of the chance for later spread (metastasis) and treatment options.
·        Cancer staging can be complex, so please ask your doctor to explain it to you in a way you can understand.

Stage Primary Tumor Lymph Node Metastasis
 0 In situ (within epidermis only) No regional lymph node metastasis No distant metastasis
 I  Clinical* ≤ 2 cm maximum tumor dimension Nodes negative by clinical exam
(no pathological exam performed)
No distant metastasis
 I  Pathological** ≤ 2 cm maximum tumor dimension Nodes negative by pathologic exam No distant metastasis
 IIA  Clinical > 2 cm tumor dimension Nodes negative by clinical exam
(no pathological exam performed)
No distant metastasis
 IIA  Pathological > 2 cm tumor dimension  Nodes negative by pathological exam No distant metastasis
 IIB  Clinical Primary tumor invades
bone, muscle, fascia, or cartilage
Nodes negative by clinical exam
(no pathological exam performed)
No distant metastasis
 IIB  Pathological Primary tumor invades
bone, muscle, fascia, or cartilage
Nodes negative by pathologic exam No distant metastasis
 III  Clinical Any size / depth tumor Nodes positive by clinical exam
(no pathological exam performed)
No distant metastasis
 IIIA  Pathological Any size / depth tumor Nodes positive by pathological exam only

(nodal disease not apparent on clinical exam)

No distant metastasis
Not detected (“unknown primary”) Nodes positive by clinical exam,

and confirmed via pathological exam

No distant metastasis
 IIIB  Pathological Any size / depth tumor Nodes positive by clinical exam, and confirmed via pathological exam OR in-transit metastasis*** No distant metastasis
 IV  Clinical Any +/- regional nodal involvement Distant metastasis
detected via clinical exam
 IV  Pathological Any +/- regional nodal involvement Distant metastasis
confirmed via pathological exam

 

* Clinical detection of nodal or metastatic disease may be via inspection, palpation, and/or imaging
**Pathological detection/confirmation of nodal disease may be via sentinel lymph node biopsy, lymphadenectomy, or fine needle biopsy; and pathological confirmation of metastatic disease may be via biopsy of the suspected metastasis
***In transit metastasis: a tumor distinct from the primary lesion and located either (1) between the primary lesion and the draining regional lymph nodes or (2) distal to the primary lesion
Reference: American Joint Committee on Cancer. Merkel Cell Carcinoma. In: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer; 2017:549.
For further details about staging, you may like to visit the United States merkelcell.org website:
https://www.merkelcell.org/testing-and-diagnosis/staging/