BACKGROUND: In patients with cutaneous melanoma, mitotic rate (MR) historically has been reported as the number of mitoses per high-power field (hpf) or per 10 hpf. The most recent revision of the American Joint Committee on Cancer melanoma staging system now incorporates MR and specifies that MR should be reported as mitoses per mm(2), with a conversion factor of 1 mm(2) equaling 4 hpf. However, because many pathologists continue to report MR in hpf units, we sought to compare the 2 conventions for reporting MR; this is important now that MR is used for staging and prognostic information. METHODS: A retrospective analysis was performed of a database that combined patients from a large multicenter study and our single-institution melanoma database. All patients with pathology reports that included MR were included. For patients with MR reported in hpf units, MR was converted to mitoses per 10 hpf. Statistical analysis was performed to test differences in Breslow thickness (BT), ulceration, sentinel lymph node (SLN) status, and overall survival (OS) (log-rank test) between the mitoses per mm(2) group versus the mitoses per 10-hpf group. RESULTS: A total of 1,148 patients were identified; of these, 759 were reported as per mm(2) and 389 were reported in hpf units. When patients were subdivided into categories of MR of 0, 1, or more than 1, there was no statistically significant difference in mean or median BT, ulceration, or SLN positivity within categories between patients with MR per mm(2) versus patients with MR reported per 10 hpf. There was also no difference in OS between groups. Subdividing into smaller categories of MR of 0, 1, 2, 3, 4, 5, or more than 5 did not yield different results. CONCLUSIONS: Although the American Joint Committee on Cancer staging system reports a conversion factor for MR of 1 mm(2) equals 4 hpf, no clinically meaningful differences in predictors of prognosis (BT, ulceration, SLN positivity) or OS were seen between groups when a conversion factor of 1 mm(2) equaling 10 hpf was used. Therefore, for practical purposes, MR reported per 10 hpf approximates MR per mm(2).
BACKGROUND: In patients with cutaneous melanoma, mitotic rate (MR) historically has been reported as the number of mitoses per high-power field (hpf) or per 10 hpf. The most recent revision of the American Joint Committee on Cancer melanoma staging system now incorporates MR and specifies that MR should be reported as mitoses per mm(2), with a conversion factor of 1 mm(2) equaling 4 hpf. However, because many pathologists continue to report MR in hpf units, we sought to compare the 2 conventions for reporting MR; this is important now that MR is used for staging and prognostic information. METHODS: A retrospective analysis was performed of a database that combined patients from a large multicenter study and our single-institution melanoma database. All patients with pathology reports that included MR were included. For patients with MR reported in hpf units, MR was converted to mitoses per 10 hpf. Statistical analysis was performed to test differences in Breslow thickness (BT), ulceration, sentinel lymph node (SLN) status, and overall survival (OS) (log-rank test) between the mitoses per mm(2) group versus the mitoses per 10-hpf group. RESULTS: A total of 1,148 patients were identified; of these, 759 were reported as per mm(2) and 389 were reported in hpf units. When patients were subdivided into categories of MR of 0, 1, or more than 1, there was no statistically significant difference in mean or median BT, ulceration, or SLN positivity within categories between patients with MR per mm(2) versus patients with MR reported per 10 hpf. There was also no difference in OS between groups. Subdividing into smaller categories of MR of 0, 1, 2, 3, 4, 5, or more than 5 did not yield different results. CONCLUSIONS: Although the American Joint Committee on Cancer staging system reports a conversion factor for MR of 1 mm(2) equals 4 hpf, no clinically meaningful differences in predictors of prognosis (BT, ulceration, SLN positivity) or OS were seen between groups when a conversion factor of 1 mm(2) equaling 10 hpf was used. Therefore, for practical purposes, MR reported per 10 hpf approximates MR per mm(2).
Authors: A Caldarella; L Fancelli; G Manneschi; A Chiarugi; P Nardini; E Crocetti Journal: J Cancer Res Clin Oncol Date: 2015-06-26 Impact factor: 4.553
Authors: Davide Barbagallo; Angela Caponnetto; Duilia Brex; Federica Mirabella; Cristina Barbagallo; Giovanni Lauretta; Antonio Morrone; Francesco Certo; Giuseppe Broggi; Rosario Caltabiano; Giuseppe M Barbagallo; Vittoria Spina-Purrello; Marco Ragusa; Cinzia Di Pietro; Thomas B Hansen; Michele Purrello Journal: Cancers (Basel) Date: 2019-02-07 Impact factor: 6.639
Authors: Eddy C Hsueh; James R DeBloom; Jonathan Lee; Jeffrey J Sussman; Kyle R Covington; Brooke Middlebrook; Clare Johnson; Robert W Cook; Craig L Slingluff; Kelly M McMasters Journal: J Hematol Oncol Date: 2017-08-29 Impact factor: 17.388