Mitotic rate measures how quickly cancer cells are dividing and growing. The mitotic rate listed on your cancer pathology report helps your healthcare provider better understand your melanoma diagnosis and develop atreatmentstrategy.
This article explains mitotic rate, what it means, and why it’s important.
What Mitotic Rate Means
Mitotic rate (MR) describes how fast cancer cells are dividing and growing. It is listed on your pathology report along with information including:
If you have a suspicious lesion or mole, your healthcare provider will send abiopsyspecimen to the pathologist. The pathologist will examine the sample under a microscope. If malignant (cancerous) cells are found, your healthcare provider may order other tests to determine itsstageand find out whether it has spread.
To measure MR, the pathologist examines the surgically removed tumor with a microscope and manually counts the number of cells exhibiting mitosis. Mitosis is an easily identifiable characteristic of dividing cells. The measurement is given as the number of mitoses per square millimeter.
The higher the mitotic count, the more likely the tumor is to have metastasized (spread).This is because rapidly dividing cells are more likely to invade the blood or lymphatic vessels and thus spread around the body.
Research has shown that the odds of survival for patients with melanoma are better for people with a lower mitotic rate. For example, people with a mitotic rate of 0 mitoses per square mm have an average five-year overall survival rate of 97.3%, while those with a mitotic rate of 4 to 10 mitoses per square mm have an average five-year overall survival rate of 73%.A higher MR is also associated with an increased risk of recurrence.Additionally, the mitotic rate can help predict if your sentinel lymph node biopsy will be positive or not.A sentinel lymph node is the first lymph node where cancer is most likely to spread.
Research has shown that the odds of survival for patients with melanoma are better for people with a lower mitotic rate. For example, people with a mitotic rate of 0 mitoses per square mm have an average five-year overall survival rate of 97.3%, while those with a mitotic rate of 4 to 10 mitoses per square mm have an average five-year overall survival rate of 73%.A higher MR is also associated with an increased risk of recurrence.
Additionally, the mitotic rate can help predict if your sentinel lymph node biopsy will be positive or not.A sentinel lymph node is the first lymph node where cancer is most likely to spread.
How Important Is Mitotic Rate in Melanoma?
Many studies have confirmed that the mitotic rate is a significant predictor of outcomes in patients with melanoma, although some controversy still exists. Two issues are under debate:
Although MR has no role in the current staging system for melanoma, research has demonstrated that it is a more important prognostic factor than ulceration, which does have an important role in staging.
Some healthcare providers, however, believe that the mitotic rate is not anindependentprognostic factor because it is closely related to tumor (Breslow) thickness and ulceration.
For example, the American Academy of Dermatology’s current guidelines recommend including mitotic rate on the pathology report.Other experts argue that measuring the MR should only be done in large academic (university) medical centers for future research purposes.
If the MR isn’t included in your pathology report, ask your healthcare provider about their reasoning for excluding it.
Talking With Your Healthcare Provider
Always request a copy of your pathology report. Read it and ask your healthcare provider questions about it. Don’t hesitate to get a second opinion about the diagnosis from a specialist, such as adermatopathologist.
A knowledgeable patient is an empowered patient and one who can make better treatment choices that lead to better outcomes.
Summary
In melanoma, mitotic rate is a measurement of how quickly cancer cells are dividing and growing. It appears on your pathology report along with other measurements like Breslow thickness and ulceration.
Mitotic rate is not currently used to determine cancer staging, but it can help your healthcare team judge potential outcomes and develop a treatment strategy.
9 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Melanoma Research Alliance.Breslow depth and Clark level Breslow depth.AIM at Melanoma Foundation.Understanding your pathology report.Ghasemi Basir HR, Alirezaei P, Ahovan S, Moradi A.The relationship between mitotic rate and depth of invasion in biopsies of malignant melanoma.Clin Cosmet Investig Dermatol. 2018;11:125-130. doi:10.2147/CCID.S158043Patuzzo R, Mattavelli I, Gallino G, et al.The prognostic role of mitotic rate in cutaneous malignant melanoma: Evidence from a multicenter study on behalf of the Italian Melanoma Intergroup.Cancer. 2023;129(15):2331-2340. doi:10.1002/cncr.34824von Schuckmann LA, Hughes MCB, Ghiasvand R, et al.Risk of melanoma recurrence after diagnosis of a high-risk primary tumor.JAMA Dermatol. 2019;155(6):688-693. doi:10.1001/jamadermatol.2019.0440Ly CL, Blaha O, Wei W, et al.Predictive accuracy of elevated mitotic rate on lymph node positivity and recurrence in thin melanomas.Front Oncol. 2023;12:1077226. doi:10.3389/fonc.2022.1077226Wan G, Nguyen N, Liu F, et al.Prediction of early-stage melanoma recurrence using clinical and histopathologic features.NPJ Precis Oncol. 2022;6(1):79. doi:10.1038/s41698-022-00321-4Tas F, Erturk K.Ulceration vs. mitosis in cutaneous melanoma: Which is superior for predicting prognosis across clinical stages?Cancer Invest. 2022;40(10):842-851. doi:10.1080/07357907.2022.2133139Swetter SM, Tsao H, Bichakjian CK, et al.Guidelines of care for the management of primary cutaneous melanoma.J Am Acad Dermatol. 2019;80(1):208-250. doi:10.1016/j.jaad.2018.08.055Additional ReadingMelanoma. National Comprehensive Cancer Network. V1.2009.Attis MG, Vollmer RT. Mitotic rate in melanoma: a reexamination. Am J Clin Pathol. 2007;127(3):380-4. DOI:10.1309/LB7RTC61B7LC6HJ6Barnhill RL, Katzen J, Spatz A, Fine J, Berwick M. The importance of mitotic rate as a prognostic factor for localized cutaneous melanoma. J Cutan Pathol. 2005;32(4):268-73. DOI:10.1111/j.0303-6987.2005.00310.xUnderstanding a Cancer Diagnosis: Skin Melanoma. College of American Pathologists.
9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Melanoma Research Alliance.Breslow depth and Clark level Breslow depth.AIM at Melanoma Foundation.Understanding your pathology report.Ghasemi Basir HR, Alirezaei P, Ahovan S, Moradi A.The relationship between mitotic rate and depth of invasion in biopsies of malignant melanoma.Clin Cosmet Investig Dermatol. 2018;11:125-130. doi:10.2147/CCID.S158043Patuzzo R, Mattavelli I, Gallino G, et al.The prognostic role of mitotic rate in cutaneous malignant melanoma: Evidence from a multicenter study on behalf of the Italian Melanoma Intergroup.Cancer. 2023;129(15):2331-2340. doi:10.1002/cncr.34824von Schuckmann LA, Hughes MCB, Ghiasvand R, et al.Risk of melanoma recurrence after diagnosis of a high-risk primary tumor.JAMA Dermatol. 2019;155(6):688-693. doi:10.1001/jamadermatol.2019.0440Ly CL, Blaha O, Wei W, et al.Predictive accuracy of elevated mitotic rate on lymph node positivity and recurrence in thin melanomas.Front Oncol. 2023;12:1077226. doi:10.3389/fonc.2022.1077226Wan G, Nguyen N, Liu F, et al.Prediction of early-stage melanoma recurrence using clinical and histopathologic features.NPJ Precis Oncol. 2022;6(1):79. doi:10.1038/s41698-022-00321-4Tas F, Erturk K.Ulceration vs. mitosis in cutaneous melanoma: Which is superior for predicting prognosis across clinical stages?Cancer Invest. 2022;40(10):842-851. doi:10.1080/07357907.2022.2133139Swetter SM, Tsao H, Bichakjian CK, et al.Guidelines of care for the management of primary cutaneous melanoma.J Am Acad Dermatol. 2019;80(1):208-250. doi:10.1016/j.jaad.2018.08.055Additional ReadingMelanoma. National Comprehensive Cancer Network. V1.2009.Attis MG, Vollmer RT. Mitotic rate in melanoma: a reexamination. Am J Clin Pathol. 2007;127(3):380-4. DOI:10.1309/LB7RTC61B7LC6HJ6Barnhill RL, Katzen J, Spatz A, Fine J, Berwick M. The importance of mitotic rate as a prognostic factor for localized cutaneous melanoma. J Cutan Pathol. 2005;32(4):268-73. DOI:10.1111/j.0303-6987.2005.00310.xUnderstanding a Cancer Diagnosis: Skin Melanoma. College of American Pathologists.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Melanoma Research Alliance.Breslow depth and Clark level Breslow depth.AIM at Melanoma Foundation.Understanding your pathology report.Ghasemi Basir HR, Alirezaei P, Ahovan S, Moradi A.The relationship between mitotic rate and depth of invasion in biopsies of malignant melanoma.Clin Cosmet Investig Dermatol. 2018;11:125-130. doi:10.2147/CCID.S158043Patuzzo R, Mattavelli I, Gallino G, et al.The prognostic role of mitotic rate in cutaneous malignant melanoma: Evidence from a multicenter study on behalf of the Italian Melanoma Intergroup.Cancer. 2023;129(15):2331-2340. doi:10.1002/cncr.34824von Schuckmann LA, Hughes MCB, Ghiasvand R, et al.Risk of melanoma recurrence after diagnosis of a high-risk primary tumor.JAMA Dermatol. 2019;155(6):688-693. doi:10.1001/jamadermatol.2019.0440Ly CL, Blaha O, Wei W, et al.Predictive accuracy of elevated mitotic rate on lymph node positivity and recurrence in thin melanomas.Front Oncol. 2023;12:1077226. doi:10.3389/fonc.2022.1077226Wan G, Nguyen N, Liu F, et al.Prediction of early-stage melanoma recurrence using clinical and histopathologic features.NPJ Precis Oncol. 2022;6(1):79. doi:10.1038/s41698-022-00321-4Tas F, Erturk K.Ulceration vs. mitosis in cutaneous melanoma: Which is superior for predicting prognosis across clinical stages?Cancer Invest. 2022;40(10):842-851. doi:10.1080/07357907.2022.2133139Swetter SM, Tsao H, Bichakjian CK, et al.Guidelines of care for the management of primary cutaneous melanoma.J Am Acad Dermatol. 2019;80(1):208-250. doi:10.1016/j.jaad.2018.08.055
Melanoma Research Alliance.Breslow depth and Clark level Breslow depth.
AIM at Melanoma Foundation.Understanding your pathology report.
Ghasemi Basir HR, Alirezaei P, Ahovan S, Moradi A.The relationship between mitotic rate and depth of invasion in biopsies of malignant melanoma.Clin Cosmet Investig Dermatol. 2018;11:125-130. doi:10.2147/CCID.S158043
Patuzzo R, Mattavelli I, Gallino G, et al.The prognostic role of mitotic rate in cutaneous malignant melanoma: Evidence from a multicenter study on behalf of the Italian Melanoma Intergroup.Cancer. 2023;129(15):2331-2340. doi:10.1002/cncr.34824
von Schuckmann LA, Hughes MCB, Ghiasvand R, et al.Risk of melanoma recurrence after diagnosis of a high-risk primary tumor.JAMA Dermatol. 2019;155(6):688-693. doi:10.1001/jamadermatol.2019.0440
Ly CL, Blaha O, Wei W, et al.Predictive accuracy of elevated mitotic rate on lymph node positivity and recurrence in thin melanomas.Front Oncol. 2023;12:1077226. doi:10.3389/fonc.2022.1077226
Wan G, Nguyen N, Liu F, et al.Prediction of early-stage melanoma recurrence using clinical and histopathologic features.NPJ Precis Oncol. 2022;6(1):79. doi:10.1038/s41698-022-00321-4
Tas F, Erturk K.Ulceration vs. mitosis in cutaneous melanoma: Which is superior for predicting prognosis across clinical stages?Cancer Invest. 2022;40(10):842-851. doi:10.1080/07357907.2022.2133139
Swetter SM, Tsao H, Bichakjian CK, et al.Guidelines of care for the management of primary cutaneous melanoma.J Am Acad Dermatol. 2019;80(1):208-250. doi:10.1016/j.jaad.2018.08.055
Melanoma. National Comprehensive Cancer Network. V1.2009.Attis MG, Vollmer RT. Mitotic rate in melanoma: a reexamination. Am J Clin Pathol. 2007;127(3):380-4. DOI:10.1309/LB7RTC61B7LC6HJ6Barnhill RL, Katzen J, Spatz A, Fine J, Berwick M. The importance of mitotic rate as a prognostic factor for localized cutaneous melanoma. J Cutan Pathol. 2005;32(4):268-73. DOI:10.1111/j.0303-6987.2005.00310.xUnderstanding a Cancer Diagnosis: Skin Melanoma. College of American Pathologists.
Attis MG, Vollmer RT. Mitotic rate in melanoma: a reexamination. Am J Clin Pathol. 2007;127(3):380-4. DOI:10.1309/LB7RTC61B7LC6HJ6
Barnhill RL, Katzen J, Spatz A, Fine J, Berwick M. The importance of mitotic rate as a prognostic factor for localized cutaneous melanoma. J Cutan Pathol. 2005;32(4):268-73. DOI:10.1111/j.0303-6987.2005.00310.x
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