Immunohistochemistry as an accurate tool for the assessment of BRAF V600E and TP53 mutations in primary and metastatic melanoma

Evaluation of P53 immunostaining in patients with cutaneous melanoma

P53 is a tumor suppressor gene that is mutated in numerous types of cancer. The aim of the present study was to determine the frequency of this mutation in cutaneous melanomas and to conduct clinicopathological characteristics and clinical outcome association analyses with the P53 mutation. P53 immunohistochemical staining was used as a surrogate marker for P53 mutation analysis to assess P53 status. In the present study, 50 pathological samples of cutaneous melanoma from 2012 to 2018 at Chulalongkorn University (Bangkok, Thailand), were subjected to anti-P53 immunohistochemistry, followed by an examination of the association between P53 statuses and clinical and pathological characteristics, along with clinical outcomes. A positive staining for anti-P53 antibody was detected in 30% of patients (15/50) with cutaneous melanomas. Positivity was significantly associated with female sex, nodular histological subtype and Breslow level 4. Cox regression analysis revealed that an age >65.5 years and Breslow grade 4 disease were associated with mortality. The Kaplan-Meier curve revealed a shorter duration of recurrence time in the P53 mutation than P53 wild type. In the present study, P53 mutations in specific cases of cutaneous melanoma were identified. Notably, patients who were older and/or had a Breslow score of 4 exhibited an increased risk of mortality. These findings suggested the potential involvement of P53 mutations in cutaneous melanoma, highlighting the necessity for further investigations to improve understanding of their roles.

The Pathology according to p53 Pathway

BACKGROUND

Observations play a pivotal role in the progress of science, including in pathology. The cause of a disease such as cancer is analyzed by breaking it down into smaller organs, tissues, cells, and molecules. The current standard cancer diagnostic procedure, microscopic observation, relies on preserved morphological characteristics. In contrast, molecular analyses explore oncogenic pathway activation that leads to genetic mutations and aberrant protein expression. Such molecular analyses could potentially identify therapeutic targets and has gained considerable attention in clinical oncology.

SUMMARY

This review summarizes the cardinal biomarkers of the p53 pathway, p53, p16, and mouse double minute 2 (MDM2), in the context of traditional surgical pathology and emerging genomic oncology. The p53 pathway, which is dysregulated in more than a half of all cancers, can be applied in several diagnostic settings. A four-classification model of immunophenotype for p53 pathway gene status, tumor types with a high frequency of abnormalities for each p53 pathway gene, and a minimal p53 pathway immunohistochemical panel is also described.

KEY MESSAGES

Immunohistochemistry of oncogenic signals should be interpreted according to molecular findings based on genomic oncology, in addition to the microscopic findings of diagnostic pathology.