The short answer
Head and neck cancer is several diseases, and the follow-up numbers here come from NCI's oropharyngeal summary, so they fit people whose treatment included radiation to the neck. For them NCI reports an underactive thyroid in 30 to 40 percent after external beam radiation to the whole thyroid gland. Dry mouth is the most common lasting effect, and it usually eases with time. Someone treated with surgery alone, or at a different site, will have a different list.
For people who had external beam radiation covering the whole thyroid gland, NCI reports an underactive thyroid in 30 to 40 percent. One report of two randomized trials, followed a median of about 41 months, put it at 55 percent.
Most of those thyroid cases were picked up on a blood test before symptoms appeared.
In one oropharyngeal radiation series NCI reports, moderate or worse dry mouth affected 55 percent of people at six months. It fell to 25 percent at one year and 16 percent at two years.
Jawbone breakdown after radiation occurred in 6 percent in the same trial, which is why dental care belongs in the plan.
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The full explanation.
Which numbers on this page apply to you
"Head and neck cancer" covers the oropharynx, larynx, hypopharynx, oral cavity, nasopharynx, salivary glands and sinuses, and NCI keeps a separate summary for each. The figures below are drawn from the oropharyngeal summary, and most of them describe people whose treatment included radiation to the neck. If you had surgery alone, or your tumor started somewhere else, ask your team which of these late effects are on your list and which are not. The questions still work; the percentages may not be yours.
The thyroid check after neck radiation
Radiation to the neck often hits the thyroid gland. NCI reports that an underactive thyroid follows in 30 to 40 percent of people who had external beam radiation to the whole gland.
One study set it higher. In two randomized trials followed for a median of about 41 months, 55 percent developed an underactive thyroid. Most of those cases were picked up on a blood test before symptoms appeared.
NCI says thyroid function is checked before treatment and as part of follow-up afterwards. Ask when yours was last drawn and when it is due again.
Dry mouth, and why teeth come first
Dry mouth is the most common lasting effect of radiation here. In one NCI trial report, moderate or worse dry mouth affected 55 percent of people at six months. It fell to 25 percent at one year and 16 percent at two years.
That downward curve matters. Dryness is often worst early and improves.
Teeth are the part people are not warned about. In the same trial, jawbone breakdown after radiation occurred in 6 percent. Dental care before, during and after radiation is not cosmetic. Ask who your dentist is going to be.
Swallowing needs practice
Swallowing muscles stiffen if they are not used. Ask to be referred to a speech and swallowing therapist, and ask for exercises rather than only advice.
If you still have a feeding tube, ask what has to happen before it comes out.
Hearing after cisplatin
Cisplatin can affect hearing. Ask whether a hearing test is worth doing, especially if you notice ringing or trouble following speech in a noisy room.
A stiff neck and a tight jaw
Neck tissue can thicken and the jaw can open less far. NCI names this stiffening as a known effect of treatment in this region.
Stretching and therapy are easier to start early than to catch up on later. Ask for a referral rather than waiting to see if it settles.
Questions for the survivorship visit
- How often should my thyroid blood test be repeated?
- Which dentist follows me now, and how often?
- Why can a tooth not simply be pulled after radiation?
- Will my dry mouth improve, and what helps in the meantime?
- Can I see a speech and swallowing therapist?
- Should I have my hearing tested?
- What is the plan for my neck stiffness and jaw opening?
Ask for a written list of every treatment you had, including radiation dose and drug names. Every specialist you meet from here will ask for it.
Related pages
Cancer Staging and Biomarker Testing explain the terms that show up in head and neck cancer follow-up notes. Clinical Trial vs Standard Treatment, Palliative Care, and Questions to Ask Your Doctor cover what to raise at a head and neck cancer survivorship visit.
Where this comes from
These questions were drawn from current patient guidance for head and neck cancer:
Words to know
Tap any term to see what it means.
Common questions
Will my dry mouth get better?
Often, yes. In one NCI trial report, moderate or worse dry mouth affected 55 percent of people at six months, 25 percent at one year and 16 percent at two years. Dryness is often worst early and improves.
Why can a tooth not simply be pulled after radiation?
Jawbone breakdown after radiation occurred in 6 percent of people in one NCI trial report. That is why dental care before, during and after radiation is not cosmetic. Ask who your dentist is going to be.
Should I have my hearing tested?
Ask, especially if you had cisplatin and you notice ringing or trouble following speech in a noisy room. Cisplatin can affect hearing.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
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Your next step
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Plain-language explanation of the published sources cited on this page. AI-assisted, source-checked, not clinician-reviewed.
Sources last checked: 2026-08-13 what this meansLast updated: 2026-08-19Next planned review: 2028-07-30
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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Related articles
- What Is Head and Neck Cancer?
- Cancer Staging: What the Stage Means
- Biomarker Testing and Precision Medicine
- Getting a Second Opinion After a Diagnosis
- Questions to Ask About Head and Neck Cancer Treatment
- Head and Neck Cancer Recurrence: What to Ask
- Metastatic Head and Neck Cancer: What to Ask
- Cancer Survivorship and Life After Treatment
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