Squamous cell carcinoma of the bladder does not promote high-risk HPV

High-risk human papilloma virus (HPV) infection occurs rarely in patients with squamous cell carcinoma (SCC) of the bladder, despite having an aggressive histologic subtype, a study has found.

Researchers looked at 207 patients with SCCs of the bladder (mean age at the time of diagnosis, 66 years; 43.5 percent female). Of these patients, 133 (64.3 percent) had a smoking history and 83 (40.1 percent) had medical conditions leading to chronic bladder irritation such as stones, indwelling catheters, and chronic urinary tract infection. None had a history of Schistosoma infection.

The majority (75 percent) of patients presented with a higher-stage (>pT2) disease at the time of cystectomy. Mean tumour size was 5.6 cm, and 36 (17 percent) patients had lymph node positive disease.

Of the 204 patients included in the p16 IHC and high-risk HPV ISH analyses, 52 (25 percent) exhibited diffuse p16 expression and only a single patient (0.5 percent) had high-risk HPV.

Over a mean follow-up of 4.6 years, 76 patients (36.7 percent) had disease recurrence and 90 (43.5 percent) died from SCC of the bladder. The mean overall survival was 9.52 years, time-to cancer-specific mortality was 17.0 years, and recurrence-free survival was 8.70 years.

Significant predictors of cancer-specific mortality were tumour size (hazard ratio [HR], 1.23), number of lymph nodes removed (HR, 0.98), number of positive lymph nodes (HR, 1.28), and perineural invasion (HR, 2.19).

In genital and oral cancers, high-risk HPV has been linked to the overexpression of the p16 protein, the researchers noted. However, this does not appear to be the case for bladder cancer, specifically SCC. This discrepancy may be explained by cross contamination of close regional HPV-driven SCCs in previous studies.