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Merkel Cell Carcinoma Treatment (PDQ®)

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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
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]
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

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 TNM

To 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
Stage Description
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
Stage Description
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.
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
Table 5. Distant Metastasis (M)a
Stage Description
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

  1. Andea AA, Coit DG, Amin B, et al.: Merkel cell carcinoma: histologic features and prognosis. Cancer 113 (9): 2549-58, 2008. [PUBMED Abstract]
  2. Yiengpruksawan A, Coit DG, Thaler HT, et al.: Merkel cell carcinoma. Prognosis and management. Arch Surg 126 (12): 1514-9, 1991. [PUBMED Abstract]
  3. Allen PJ, Zhang ZF, Coit DG: Surgical management of Merkel cell carcinoma. Ann Surg 229 (1): 97-105, 1999. [PUBMED Abstract]
  4. 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]
  5. American Joint Committee on Cancer: AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer, 2002.
  6. 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]
  7. 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.
  8. 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]
  • Updated: April 9, 2015