Last Modified: 07/16/2012
Stage Information for Merkel Cell Carcinoma
Previously, five competing staging systems have been used to describe Merkel cell carcinoma (MCC) in most publications.
Table 2. Five Previously Used Competing Merkel Cell Carcinoma Staging Systems| First Author | Publication Date | Institution(s) | No. of Patients in Case Series | Dates of Cases |
| Yiengpruksawan et al.[2] | 1991 | MSKCCa | 77 | 1969–1989 |
| Allen et al.[3] | 1999 | MSKCCa | 102 | 1969–1996 |
| Allen et al.[4] | 2005 | MSKCCa | 250 | 1970–2002 |
| American Joint Committee on Cancer[5] | 2002 | N/A | N/A | |
| Clark et al.[6] | 2007 | Westmead Hospital, Sydney, Australia | 110 | |
| Princess Margaret Hospital/University Health Network, Toronto, Canada | ||||
| Sydney Head and Neck Cancer Institute/Royal Prince Alfred Hospital, Sydney, Australia |
| MSKCC = Memorial Sloan Kettering Cancer Center; N/A = Not applicable. | ||||
| aThe MSKCC system has evolved over time. MSKCC authors have published one additional case series with 256 patients.[1] |
These staging systems are highly inconsistent with each other. Indeed, stage III disease can mean anything from advanced local disease to nodal disease to distant metastatic disease. Furthermore, all MCC staging systems in use have been based on fewer than 300 patients.
Definitions of TNMTo address these concerns, a new MCC-specific consensus staging system was developed by the American Joint Committee on Cancer (AJCC) to define Merkel cell carcinoma, as shown in tables 3, 4, 5, and 6.[7] Prior to the publication of this new system, the AJCC advocated using the nonmelanoma staging system.
Table 3. Primary Tumor (T)a| aReprinted with permission from AJCC: Merkel cell carcinoma. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 315-23. | |
| TX | Primary tumor cannot be assessed. |
| T0 | No evidence of primary tumor (e.g., nodal/metastatic presentation without associated primary). |
| Tis | In situ primary tumor. |
| T1 | ≤2 cm maximum tumor dimension. |
| T2 | >2 cm but ≤5 cm maximum tumor dimension. |
| T3 | >5 cm maximum tumor dimension. |
| T4 | Primary tumor invades bone, muscle, fascia, or cartilage. |
Table 4. Regional Lymph Nodes (N)a
| NX | Regional lymph nodes cannot be assessed. |
| N0 | No regional lymph nodes metastasis. |
| cN0 | Nodes negative by clinical examb (no pathologic node exam performed). |
| pN0 | Nodes negative by pathologic exam. |
| N1 | Metastases in regional lymph node(s). |
| N1a | Micrometastasis.c |
| N1b | Macrometastasis.d |
| N2 | In transit metastasis.e |
| aReprinted with permission from AJCC: Merkel cell carcinoma. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 315-23. | |
| bClinical detection of nodal disease may be via inspection, palpation, and/or imaging. | |
| cMicrometastases are diagnosed after sentinel or elective lymphadenectomy. | |
| dMacrometastases are defined as clinically detectable nodal metastases confirmed by therapeutic lymphadenectomy or needle biopsy. | |
| eIn 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. |
Table 5. Distant Metastasis (M)a
| aReprinted with permission from AJCC: Merkel cell carcinoma. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 315-23. | |
| M0 | No distant metastasis. |
| M1 | Metastases beyond regional lymph nodes. |
| M1a | Metastases to skin, subcutaneous tissues, or distant lymph nodes. |
| M1b | Metastasis to lung. |
| M1c | Metastases to all other visceral sites. |
Table 6. Anatomic Stage/Prognostic Groupsa
| Stage | T | N | M |
| aReprinted with permission from AJCC: Merkel cell carcinoma. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 315-23. | |||
| 0 | Tis | N0 | M0 |
| IA | T1 | pN0 | M0 |
| IB | T1 | cN0 | M0 |
| IIA | T2/T3 | pN0 | M0 |
| IIB | T2/T3 | cN0 | M0 |
| IIC | T4 | N0 | M0 |
| IIIA | Any T | N1a | M0 |
| IIIB | Any T | N1b/N2 | M0 |
| IV | Any T | Any N | M1 |
Before the new AJCC consensus staging system was published, the most recent MSKCC four-stage system was favored because it was based on the largest number of patients and was the best validated.[1] The stages in the MSKCC system included:
- Stage I: local disease <2 cm.
- Stage II: local disease ≥2 cm.
- Stage III: regional nodal disease.
- Stage IV: distant metastatic disease.
One group has suggested a list of 12 elements that should be described in pathology reports of resected primary lesions and nine elements to be described in pathology reports of sentinel lymph nodes. The prognostic significance of these elements has not been validated prospectively.[8] The 2009 AJCC staging manual also specifies a variety of factors which should be collected prospectively on pathology reports.
References- Andea AA, Coit DG, Amin B, et al.: Merkel cell carcinoma: histologic features and prognosis. Cancer 113 (9): 2549-58, 2008. [PUBMED Abstract]
- Yiengpruksawan A, Coit DG, Thaler HT, et al.: Merkel cell carcinoma. Prognosis and management. Arch Surg 126 (12): 1514-9, 1991. [PUBMED Abstract]
- Allen PJ, Zhang ZF, Coit DG: Surgical management of Merkel cell carcinoma. Ann Surg 229 (1): 97-105, 1999. [PUBMED Abstract]
- Allen PJ, Bowne WB, Jaques DP, et al.: Merkel cell carcinoma: prognosis and treatment of patients from a single institution. J Clin Oncol 23 (10): 2300-9, 2005. [PUBMED Abstract]
- American Joint Committee on Cancer.: AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer, 2002.
- Clark JR, Veness MJ, Gilbert R, et al.: Merkel cell carcinoma of the head and neck: is adjuvant radiotherapy necessary? Head Neck 29 (3): 249-57, 2007. [PUBMED Abstract]
- Merkel cell carcinoma. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 315-23.
- Bichakjian CK, Lowe L, Lao CD, et al.: Merkel cell carcinoma: critical review with guidelines for multidisciplinary management. Cancer 110 (1): 1-12, 2007. [PUBMED Abstract]