October is Breast Cancer Awareness Month, observed every October 1st through 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, radiation, and immunotherapy all carry oral side effects. This month serves as an important reminder for dental offices to ensure they are asking patients if they have been or are currently being treated for cancer. The American Cancer Society projects roughly 2,114,850 new cancer diagnoses in the US in 2026, and the most recent count put the number of people living with a history of cancer at 18.6 million. A significant portion of those patients will sit in a general or hygiene chair during active treatment or years into survivorship, whether or not the practice thinks to ask whether a patient has undergone treatment for cancer at the time of intake.
What most cancer treatments do to the mouth
Two oral complications show up across nearly every kind of cancer treatment, not just one protocol or one diagnosis. The first is oral mucositis, which the ADA describes as painful and potentially debilitating. It's also the most common side effect of radiation therapy and chemotherapy, according to the National Cancer Institute. The second is dry mouth. Radiation can damage the salivary glands, and dry mouth raises the risk of tooth decay.
Radiation to the head and neck adds a longer-term risk
For patients treated with radiation in the head and neck region, osteoradionecrosis, a breakdown of jawbone tissue that has lost much of its blood supply, has a prevalence estimated at 2% to 15% depending on the study population. One 2022 study, tracking 572 people through head and neck radiotherapy, found 6.1% developed exposed bone and 3.1% met the criteria for osteoradionecrosis within two years. A smaller share of patients develop mucositis or dry mouth, but it can surface months or years after treatment ends, which is why a patient's cancer history belongs in the chart long after the cancer itself is resolved.
It’s important to know about the 4-week window
Timing is important. It is recommended that patients see a dentist approximately four weeks before starting cancer treatment, when possible, so any needed dental work has time to heal. The American Dental Association (ADA) also calls for clearing up existing dental, gum, and mucosal infections before therapy begins. That window matters because dental care before chemotherapy and radiation can lower the risk of infection. If a patient tells your practice, "I'm starting chemo next month," get them on the schedule right away.
What dental teams 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.
- 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 side effects are common, through mucositis, dry mouth, 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.
