Background/Introduction
Vulvar cancer is an uncommon gynaecological malignancy in Australia, with approximately 420 new cases each year. The most common histological type is squamous cell carcinoma, of which precursor lesions can be either human papillomavirus (HPV)-dependent, characterised by p16 overexpression or HPV-independent. HPV-independent vulvar cancers can arise from vulvar dermatoses, such as lichen sclerosus, and are often characterised by TP53 mutations. Some previous studies have shown prognostic significance of p16 and p53 expression in patients with squamous vulvar carcinomas.
Objectives
To identify the whether p53 and p16 immunohistochemistry results have prognostic value in vulvar cancer patients, in a retrospective review of patients treated at a single institution.
Methods
A retrospective chart analysis was performed for all patients diagnosed with vulva cancer over a 10 year period (2010-2019) at one institution in Sydney, Australia. Overall, 133 patients were newly diagnosed with vulvar cancer in this time period, of which 111 were squamous cell carcinomas. Pathology for each patient was analysed to determine whether immunohistochemical analysis had been performed, and the results recorded. Kaplan Meier and Log Rank analyses were used to determine the impact of these p16 and p53 immunohistochemistry results on survival outcomes.
Results and Conclusions
Of 133 vulvar cancer cases at this institution over the 10 year time period, 111 were squamous cell carcinomas. Of these, immunohistochemistry results were available for 74 patients (66.67%). 39 patients were p16 positive, 6 patients were p53 positive, 3 patients were positive for both p16 and p53. Follow-up data was available for an average of 4.35 years post diagnosis. Comparing patients that were p16 positive to p53 positive, both p16 and p53 positive and ‘others’ (which included patients for whom results were not available and those for whom immunohistochemistry analyses were not performed), p16 positive group had the highest overall survival, and p53 had the lowest overall survival, a difference in outcomes that was statistically significant.
Figure 1: Kaplan Meier curve determining survival outcomes by immunohistochemistry analysis of vulva cancer patients