October is Breast Cancer Awareness Month, observed every October 1^st through the 31st. It's also a reminder to look at something broader than one diagnosis: how cancer treatment, regardless of the cancer being treated, tends to show up in the dental chair. Chemotherapy and radiation can both affect the mouth, and immunotherapy has its own oral complications. This month is a good time for dental offices to make sure they are asking patients whether they have been, or currently are being, treated for cancer. The Canadian Cancer Society projects an estimated 254,100 new cancer diagnoses in Canada in 2026. A significant portion of those patients will sit in a general or hygiene chair during active treatment and in the years after, whether or not the practice asks about it at intake.

What most cancer treatments do to the mouth

Both radiation and chemotherapy can affect the lining of the mouth and the salivary glands. For patients, that can mean dry mouth, tooth decay, and other dental problems, which is why the mouth deserves attention at every stage of treatment.

Radiation to the head and neck adds a longer-term risk

For patients treated with radiation in the head and neck region specifically, osteoradionecrosis, or bone death caused by radiation, is a known risk. The Canadian Cancer Society notes that a dentist should discuss it with the radiation oncologist before any dental surgery after high-dose radiation to the face or mouth. One 2022 study, tracking 572 people through head and neck radiotherapy, found that 6.1% developed exposed bone and 3.1% met the criteria for osteoradionecrosis within two years. In Canada, head and neck cancer is projected to account for 8,200 new diagnoses in 2026.

Get patients in before treatment starts

Timing is important. For head and neck cancer, Alberta Health Services' clinical practice guideline says teeth with a poor prognosis should be removed at least 14 to 21 days before cancer therapy, and other dental problems treated as soon as possible so they don't delay treatment. If a patient tells your practice, "I'm starting treatment next month," get them on the schedule right away.

What the dental team can do once treatment is underway

Care during active treatment tends to be conservative and coordinated, built around a shared plan with the oncology team and a simple home-care routine: a soft-bristle brush, saline or baking soda rinses, fluoride gel, and no alcohol-based rinses.

To put this into practice:

• Ask every patient at intake and recall whether they are being treated for cancer, have been, or are about to start.
• Include immunotherapy in that question. According to a September 2025 clinical practice statement, a dental evaluation before starting immunotherapy may be beneficial. It can help prevent dental emergencies during treatment and gives patients a chance to learn basic oral self-care.
• If a patient is about to begin treatment, get them on the schedule quickly and contact their oncology team.
• Record their treatment history in the chart so it carries through every future visit.

What it means going forward

Whatever cancer a patient is being treated for, oral health can be affected, through dry mouth, tooth decay, or, for some head and neck patients, a jawbone complication. This month is a reminder that none of this requires a special campaign. Tracking cancer treatment history, the same way a practice tracks any other medical condition is one more way to support patient wellness.