J Cancer Res Clin Oncol DOI 10.1007/s00432-015-2007-1
ORIGINAL ARTICLE – CANCER RESEARCH
How staging of thin melanoma is changed after the introduction of TNM 7th edition: a population‑based analysis A. Caldarella1 · L. Fancelli2 · G. Manneschi1 · A. Chiarugi3 · P. Nardini3 · E. Crocetti1
Received: 30 March 2015 / Accepted: 14 June 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Introduction In 2009, the American Joint Committee on Cancer (AJCC) incorporated the tumor mitotic rate in the melanoma pathological TNM staging system. To investigate the effect of this change on the pT1 substaging of primary cutaneous melanomas, we reclassified the cases collected by a cancer registry according to the 6th and the 7th editions of AJCC melanoma staging. Methods Patients with pathological T1 melanoma diagnosed in the period 2000–2008 were selected from Tuscan Cancer Registry. The histological reports were reviewed and pT1 melanomas classified according to both the 6th and the 7th editions of the AJCC staging system. The shift of melanomas between pT1 substages was analyzed. Results Among the 242 pT1 melanomas collected in the study period and with mitotic index available, there were 202 (83 % of all pT1) and 175 (72 %) pT1a, according to the 6th and the 7th editions of the AJCC melanoma staging, respectively. When the 7th edition was used, 20 % of all pT1a melanomas shifted to pT1b, and 32 % of all pT1b melanomas shifted to pT1a. A poor level agreement between the two TNM staging systems, measured by the Cohen’s kappa coefficient, was found (K = 0.37).
* A. Caldarella [email protected] 1
Cancer Prevention and Research Institute, Via Cosimo il Vecchio n. 2, 50141 Florence, Italy
2
Dermatology Section, Department of Surgery and Translational Medicine, School of Medicine, Florence, Italy
3
Screening and Cancer Prevention, Melanoma Prevention Service, Cancer Prevention and Research Institute, Florence, Italy
Conclusions The addition of mitotic activity to the pathological staging resulted in an increase in pT1b proportion and in a change in the classification of some cases. This modification could influence the clinical approach, with a different use of the sentinel lymph node biopsy, and underlines the role of mitosis evaluation in the management of thin melanoma patients. Keywords Melanoma · Staging system · Mitosis · TNM
Introduction Primary tumor mitotic rate, histologically defined as the number of dermal mitoses per mm2, is an important independent predictor of survival (Balch et al. 2011). In 2009, the American Joint Committee on Cancer (AJCC) updated the TNM staging of melanoma by adding the tumor mitotic rate to the TNM staging system of melanoma (de Waal et al. 2014). Mitotic rate has been added as a secondary criterion for defining pT1b melanoma and replaces Clark’s level of invasion, used in melanoma staging in the past. Primary tumor mitotic rate is now a required element for the 7th edition melanoma staging. Multiple thresholds of mitotic rate were examined statistically, and the most significant correlation with survival was identified at a threshold of at least 1/mm2. Thus, according to the 7th edition of the TNM melanoma staging system, now the subcategory pT1b is defined as melanoma in which thickness is ≤1.0 mm and that has tumor ulceration and/or at least 1 mitosis/mm2. In addition, some new guidelines suggest to offer sentinel lymph node biopsy to patients with melanoma of stage pT1b (de Waal et al. 2014).
13
To investigate the effect of the introduction of mitotic rate in the pT1 substaging of primary cutaneous melanomas and the clinical implication of the new staging protocol, we reclassified the cases collected by a cancer registry according to the 6th and the 7th editions of AJCC melanoma staging.
Materials and methods Patients with pathological T1 melanoma diagnosed in the period 2000–2008 resident in provinces of Florence and Prato were selected from Tuscan Cancer Registry (RTT). All primary invasive thin (≤1 mm) melanomas diagnosed among residents in the provinces of Firenze and Prato during the period 2000–2008 were retrieved from the Tuscan Cancer Registry. This is a population-based database in which data on all newly diagnosed patients with cancer in the area of Firenze and Prato are recorded. Cases diagnosed by death certificate only or for which histological report on primitive lesion was not available were excluded. Data on tumor morphology, age at diagnosis, stage at diagnosis, date of diagnosis were already available in the RTT archive. Histological reports collected by the registry were reexamined for each case to extract information on prognostic factors such as Breslow thickness, mitotic activity, Clark level, and ulceration. In addition, through the review of hospital discharge collected by the cancer registry, the sentinel lymph node status was analyzed in a subset of patients with thin melanomas who had this procedure as part of their management. Patients without indication of mitotic count, reported as number of mitotic figures/mm2, were excluded from analysis. Mitotic rate reported as
ORIGINAL ARTICLE – CANCER RESEARCH
How staging of thin melanoma is changed after the introduction of TNM 7th edition: a population‑based analysis A. Caldarella1 · L. Fancelli2 · G. Manneschi1 · A. Chiarugi3 · P. Nardini3 · E. Crocetti1
Received: 30 March 2015 / Accepted: 14 June 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Introduction In 2009, the American Joint Committee on Cancer (AJCC) incorporated the tumor mitotic rate in the melanoma pathological TNM staging system. To investigate the effect of this change on the pT1 substaging of primary cutaneous melanomas, we reclassified the cases collected by a cancer registry according to the 6th and the 7th editions of AJCC melanoma staging. Methods Patients with pathological T1 melanoma diagnosed in the period 2000–2008 were selected from Tuscan Cancer Registry. The histological reports were reviewed and pT1 melanomas classified according to both the 6th and the 7th editions of the AJCC staging system. The shift of melanomas between pT1 substages was analyzed. Results Among the 242 pT1 melanomas collected in the study period and with mitotic index available, there were 202 (83 % of all pT1) and 175 (72 %) pT1a, according to the 6th and the 7th editions of the AJCC melanoma staging, respectively. When the 7th edition was used, 20 % of all pT1a melanomas shifted to pT1b, and 32 % of all pT1b melanomas shifted to pT1a. A poor level agreement between the two TNM staging systems, measured by the Cohen’s kappa coefficient, was found (K = 0.37).
* A. Caldarella [email protected] 1
Cancer Prevention and Research Institute, Via Cosimo il Vecchio n. 2, 50141 Florence, Italy
2
Dermatology Section, Department of Surgery and Translational Medicine, School of Medicine, Florence, Italy
3
Screening and Cancer Prevention, Melanoma Prevention Service, Cancer Prevention and Research Institute, Florence, Italy
Conclusions The addition of mitotic activity to the pathological staging resulted in an increase in pT1b proportion and in a change in the classification of some cases. This modification could influence the clinical approach, with a different use of the sentinel lymph node biopsy, and underlines the role of mitosis evaluation in the management of thin melanoma patients. Keywords Melanoma · Staging system · Mitosis · TNM
Introduction Primary tumor mitotic rate, histologically defined as the number of dermal mitoses per mm2, is an important independent predictor of survival (Balch et al. 2011). In 2009, the American Joint Committee on Cancer (AJCC) updated the TNM staging of melanoma by adding the tumor mitotic rate to the TNM staging system of melanoma (de Waal et al. 2014). Mitotic rate has been added as a secondary criterion for defining pT1b melanoma and replaces Clark’s level of invasion, used in melanoma staging in the past. Primary tumor mitotic rate is now a required element for the 7th edition melanoma staging. Multiple thresholds of mitotic rate were examined statistically, and the most significant correlation with survival was identified at a threshold of at least 1/mm2. Thus, according to the 7th edition of the TNM melanoma staging system, now the subcategory pT1b is defined as melanoma in which thickness is ≤1.0 mm and that has tumor ulceration and/or at least 1 mitosis/mm2. In addition, some new guidelines suggest to offer sentinel lymph node biopsy to patients with melanoma of stage pT1b (de Waal et al. 2014).
13
To investigate the effect of the introduction of mitotic rate in the pT1 substaging of primary cutaneous melanomas and the clinical implication of the new staging protocol, we reclassified the cases collected by a cancer registry according to the 6th and the 7th editions of AJCC melanoma staging.
Materials and methods Patients with pathological T1 melanoma diagnosed in the period 2000–2008 resident in provinces of Florence and Prato were selected from Tuscan Cancer Registry (RTT). All primary invasive thin (≤1 mm) melanomas diagnosed among residents in the provinces of Firenze and Prato during the period 2000–2008 were retrieved from the Tuscan Cancer Registry. This is a population-based database in which data on all newly diagnosed patients with cancer in the area of Firenze and Prato are recorded. Cases diagnosed by death certificate only or for which histological report on primitive lesion was not available were excluded. Data on tumor morphology, age at diagnosis, stage at diagnosis, date of diagnosis were already available in the RTT archive. Histological reports collected by the registry were reexamined for each case to extract information on prognostic factors such as Breslow thickness, mitotic activity, Clark level, and ulceration. In addition, through the review of hospital discharge collected by the cancer registry, the sentinel lymph node status was analyzed in a subset of patients with thin melanomas who had this procedure as part of their management. Patients without indication of mitotic count, reported as number of mitotic figures/mm2, were excluded from analysis. Mitotic rate reported as
