378P - Outcomes of p16 positive oropharyngeal squamous cell carcinoma treated with radiotherapy – Results from a tertiary care center in South India

Date 17 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Head and Neck Cancers
Surgery and/or Radiotherapy of Cancer
Presenter Srijith Sashidharan
Citation Annals of Oncology (2016) 27 (suppl_9): ix112-ix122. 10.1093/annonc/mdw587
Authors S. Sashidharan1, C. Prasad2, A. Ramesan Nair1, P. Chelakkot G1
  • 1Radiation Oncology, Amrita Institute of Medical Sciences, 682041 - Kochi/IN
  • 2Pathology, Amrita Institute of Medical Sciences, 682041 - Kochi/IN

Abstract

Background

HPV association with oropharyngeal squamous cell cancer (OPSCC) has been proven in landmark studies worldwide and there are ongoing studies investigating the possibility of radiation dose de escalation in HPV positive patients due to their favorable outcome . There is lack of data on HPV positivity in Indian patients while it is presumed smoking still predominates as the major etiology for OPSCC in the Indian population . p16 immunohistochemistry (IHC) is a surrogate marker for HPV positivity in OPSCC. This study evaluated the prevalence of HPV in OPSCC in the reference population, clinical differences between p16-positive and - negative OPSCC and the role of its prognostic strength in cases treated with chemoradiation.

Methods

Formalin-fixed, paraffin-embedded blocks and clinical information from OPSCC patients treated with chemoradiotherapy (or radiation alone) between 2011 and 2014 were collected retrospectively. IHC for p16 protein was carried out; overall survival (OS), progression-free survival (PFS) were calculated and the association with p16 was analysed.

Results

We analysed 57 cases of OPSCC . 51 patients were locally advanced OPSCC . The incidence of p16 positivity was 40.4% . Smoking history was present in 78.9% of OPSCC with a median pack years of 30 (8-120) . There were 16 cases of recurrences noted (28.1%) with 10 distant and 6 local recurrences . At a median follow up of 25.2 months, 3 year OS for the entire cohort was 72.4% and PFS was 64.9% . p16 positive patients had better OS (80% vs 64.9%, log rank p -0.121) and better PFS (71% vs 58.3%; p -0.19) . Association with smoking could not be done due to the lower number of non smokers.

Conclusions

There is lower incidence of p16 positivity in our study population. Smoking still continues to be associated with most cases of OPSCC. The p16 positive patients did show a trend towards improved OS and PFS; however a larger and more diverse cohort involving multiple institutions across the country is required for conclusive evidence on association with HPV and OPSCC.

Clinical trial indentification

Legal entity responsible for the study

Amrita Institute of Medical Sciences

Funding

Amrita Institute of Medical Sciences

Disclosure

All authors have declared no conflicts of interest.