I don't know why the doctor said he will only have up to 5 years? If they are going by statistics, yes, it's less than 50% 5 year survival rate with smoking related oropharyngeal and oral cancer, but is 85% with HPV positive cancer. Statistics are not crystal balls, and there are many other factors involved, like the size, thickness, depth of the tumor, the numbet of lymph nodes involved, ipsilateral or bi-lateral, their size, other negative factors like extracapsular spread or extension, perineural or lymphovascular invasion, distant metastases, a persons age, health, other comorbitities.

Chemoradiation is common with oropharyngeal cancer as organ preservation instead of surgery. You may want to find out if its HPV related, which has good prognosis, and 90% of orpharynx cancer is HPV related, and rarely occurs in the oral mouth, but basically is the same treatment, except for some clinical trials.

I had Cisplatin with a combination of two other chemo's, and then another time Erbitux with Taxotere. Erbitux was easier, but not without toxicities, and the trial with Erbitux vs Cisplatin is not completed yet to determine which has better outcome.

Good luck.