Effects of Cancer Treatment on the Oral Cavity.

A guide to what to expect.



Clinicians across the spectrum of healthcare in the community are part of a cancer patient’s treatment team. Compromised oral health prior to, during and following cancer treatment dramatically affects treatment outcomes and quality of life.

Cancer patients usually get surgery, chemotherapy and/or radiation therapy as part of their treatment protocol. Regardless of the type of cancer they have, there are changes that occur in the mouth and throat that can profoundly affect their quality of life. This is because cancer treatment can affect the oral tissues and as a result, certain oral side effects can come into play. Going forward, pre-existing or untreated oral disease can also complicate ongoing and long term cancer treatment outcomes.

Mucosal tissue, also known as mucosa or the mucous membrane, lines all body passages that communicate with the air, such as the respiratory and gastrointestinal tracts, and have cells and associated glands that secrete mucus. The part of this lining that covers the mouth, called the oral mucosa, is one of the most sensitive parts of the body and is particularly sensitive to chemotherapy and radiation. Oral complications occur in virtually all patients receiving radiation for head and neck cancers, in approximately 80 % of patients with blood cancers ( leukemias) who are stem cell transplant recipients, and in nearly 40 % of patients receiving chemotherapy.

Not all patients who undergo chemotherapy are at equal risk for developing oral complications.

There are a number of factors that affect both the frequency and severity of oral problems associated with therapy. These can be divided into:

  1. Those that are associated with the patient

  2. Those that are related to the treatment protocol.

Chemotherapy can cause mouth sores, dry mouth, increased decay, pain in the mouth and gums, peeling or burning of the tongue, infection, changes in taste, temporary decrease in your body’s ability to produce infection-fighting cells and bleeding from the gums.




Patients undergoing radiation therapy such as for head and neck cancers have a significant impact on the oral cavity. The side effects of radiation therapy can be early or delayed. Early side effects occur during the course of therapy and during the immediate post therapy period (approximately 2–3 weeks after the completion of a course of radiation therapy). Late effects can occur any time, from weeks to years later. Early side effects include skin changes like a sunburn or suntan in the treated area, hoarseness, loss of taste, redness, soreness, or pain in the mouth and throat, dry mouth, trouble swallowing, fatigue, and open sores in the mouth and throat. Late side effects include permanent loss of saliva; osteoradionecrosis of the jaw bone; narrowing or stenosis of the esophagus and or pharynx; dental caries; fibrosis; impaired wound healing; skin changes and skin cancer; lymphedema and damage to the eye, ear, nerve and neck structures.


“40% of chemotherapy and radiotherapy patients develop mucositis, or inflammation of the mucous membranes in the mouth. Mucositis can range from mild redness to mouth sores.” - The Oral Cancer Foundation estimate.

One of the most common side effects of both chemotherapy and radiation therapy is mucositis. Mucositis occurs when cancer treatments break down the cells lining the mouth (oral mucosa) and throat leaving the mucosal tissue open to ulceration and infection. It can lead to several problems, including pain, nutritional problems as a result of inability to eat, and increased risk of infection due to open sores in the mucosa. It has a significant effect on the patient’s quality of life and can affect treatment directly by requiring reduction of chemotherapy dosing. The majority of oral cancer patients receiving chemotherapy in combination with radiation will experience at least some degree of mucositis. When caused by chemotherapy, mucositis is usually due to the low white blood cell count; when caused by radiation, mucositis is usually due to the necrotic and inflammatory effect of radiation energy on oral mucosa.



Another common side effect is dry mouth due to decrease in saliva production as a direct effect of treatment. This can be long lasting and significantly affect quality of life. Radiation therapy can lead to irreversible salivary gland cell damage as these cells are very sensitive to radiation. Radiation therapy often leads to marked changes in the quantity and quality of saliva altering its consistency from watery to viscous. This change in the quality and quantity of saliva can lead to infections (mostly fungal), denture related inflammation (called stomatitis) caused by fungus/yeast, alterations in mouth pH, salivary stones and cysts, radiation caries, and burning mouth syndrome. It can lead to difficulty in eating, swallowing, and speaking, increase the risk of cavities and periodontal disease, and complicate dentures maintenance.


Proper preparation and close monitoring of your mouth, teeth and throat is paramount in decreasing the side effects of treatment and maintaining your quality of life. The next blog will talk about what steps you need to take to optimize your oral care.


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Reason to Hope

There is new research from Brigham and Women’s Hospital that indicates a Western-style diet that is rich in red and processed meat, sugar and refined grains/carbohydrates is tied to higher risk of colorectal cancer through the intestinal microbiota.  Gastroenterology, 2022;DOI:10.1053/j.gastro.2022.06.054