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Poster display session: Basic science, Endocrine tumours, Gastrointestinal tumours - colorectal & non-colorectal, Head and neck cancer (excluding thyroid), Melanoma and other skin tumours, Neuroendocrine tumours, Thyroid cancer, Tumour biology & pathology

3125 - Frequency of PIK3CA Mutations in Head and Neck Squamous Cell Carcinoma (HNSCC) in Southern Thailand.

Date

21 Oct 2018

Session

Poster display session: Basic science, Endocrine tumours, Gastrointestinal tumours - colorectal & non-colorectal, Head and neck cancer (excluding thyroid), Melanoma and other skin tumours, Neuroendocrine tumours, Thyroid cancer, Tumour biology & pathology

Topics

Tumour Site

Head and Neck Cancers

Presenters

Phatcharaporn Thongwatchara

Citation

Annals of Oncology (2018) 29 (suppl_8): viii372-viii399. 10.1093/annonc/mdy287

Authors

P.-. Thongwatchara1, P. Thongsuksai2, T. Dechaphunkul3, A. Dechaphunkul1

Author affiliations

  • 1 Unit Of Medical Oncology, Department Of Internal Medicine, Faculty of Medicine, Prince of Songkla University, 90110 - Songkhla/TH
  • 2 Department Of Pathology, Faculty of Medicine, Prince of Songkla University, 90110 - Songkhla/TH
  • 3 Otorhinolaryngology Head And Neck Surgery, Songklanagarind Hospital, 90110 - Songkhla/TH
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Resources

Abstract 3125

Background

Phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) mutations have been reported in many cancers including HNSCC. The presence of mutations have shown to associate with prognosis and might predict response to phosphoinositide 3-kinase (PI3K) inhibitors. However, the frequency of mutations is various among primary tumor locations, so this might be relevant to distinguish the possibility of treatments and outcomes among HNSCC. In this study, we examined the frequency of PIK3CA mutations in patients with oral cavity and hypopharyngeal carcinoma.

Methods

Ninety-six fresh biopsies consisted of 73 oral cavity and 23 pyriform sinus carcinoma were collected for DNA extraction. DNA samples were first investigated to ascertain a reference mutational points in PIK3CA exons 4, 9 and 20. We subsequently designed two probes labelled with two different fluorescent dyes for the wild-type and mutated alleles. Mutational analysis was further carried out by using allele-specific real time PCR.

Results

We identified mutations in 10% of patients (10 out of 96 HNSCC specimens). Among 10 mutant specimens, there were 5 missense mutations (2 samples in exon 9 (E545K) and 3 samples in exon 20 (H1047R)), and 5 silence mutation in exon 20 (T1025T). None of mutation was found in exon 4. Exon 9 mutation was detected in 2 out of 96 cases and was merely from hypopharyngeal carcinoma. In exon 20, 8 mutations were found (2 hypopharyngeal carcinoma and 6 oral cavity carcinoma). Overall frequency of mutations in three exons were 8% and 17% in oral cavity and hypopharyngeal carcinoma, respectively.Table: 1090P

Frequency of PIK3CA mutations in HNSCC

Location of HNSCC% PIK3CA mutationOverall % PIK3CA mutation
Exon 4Exon 9Exon 20in three exons
Oral cavity carcinoma0 (0/61)0 (0/73)8 (6/73)8 (6/73)
Hypopharyngeal carcinoma0 (0/21)8 (2/23)8 (2/23)17 (4/23)
Frequency of mutation10 (10/96)

Conclusions

Our study showed more frequency of PIK3CA mutations in hypopharyngeal carcinoma than oral cavity carcinoma. These results suggest that its mutation may be more involved in the carcinogenesis, and hypopharynx should be primary site of interest for further studies.

Clinical trial identification

Legal entity responsible for the study

Unit of Medical Oncology, Faculty of Medicine, Prince of Songkla University.

Funding

Faculty of Medicine, Prince of Songkla University.

Editorial Acknowledgement

Disclosure

All authors have declared no conflicts of interest.

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