There are few words in the English language that strike more fear into a person than ‘cancer.’ Even with the exponential advances of the medical and pharmaceutical professions, a cancer diagnosis can stir up a range of emotions, from anxiety to the unyielding resolve to fight.
Oral cancer is a malignancy which is not highly publicized. Even so, the devastation it can cause for the patient and their families is considerable.
Recommended course: Oral Effects and Dental Management of Chemotherapy Patients, 3rd Edition
A review of the statistics
Cancer of the oral cavity (OC) and the oropharynx (OP) comprise 2.8% of all cancers diagnosed in the United States. These cancers account for 1.8% of all cancer-related deaths (American Dental Association, 2022). The American Cancer Society estimated that there were a total of 54,000 new cases of OC and OP cancer and 11,230 deaths related to these malignancies in 2022 (Siegel, et al., 2022).
The demographics of oral cancer have changed considerably over time. Decades ago, the male to female ratio for oral cancer was 10:1. However, this ratio has been reduced to a 2:1 ratio (The Oral Cancer Foundation, 2023).
Squamous cell carcinoma (SCC) accounts for about 90% of all OC and OP diagnosed. As with any malignancy, early diagnosis is essential for decreased morbidity and survival. The five-year survival rate for localized OC and OP is 85% for localized malignancies but only 40% when there is metastasis.
Etiology of oral cancer
The long-term use of tobacco products, especially when combined with alcohol, were considered the primary oncogenic agents for the development of OC and OP malignancies.
Tobacco products contain multiple carcinogens. Alcohol is a desiccating agent, which can decrease the lubrication of the oral mucosal surfaces, which can then retain the carcinogens for an extended duration. The persistent exposure over time increases the chance for the development of OC or OP malignancies.
“Smokeless” tobacco products such as chewing tobacco are not a “safe” alternative to smoking cigarettes. They remain lodged against the oral gingival and mucosal tissues for an extended period of time, increasing carcinogen exposure.
In recent years, a new trend has emerged among the patients who have been diagnosed with OC or OP malignancies. Many of these patients have never used any tobacco product and do not consume alcoholic beverages or consume them in moderation. Scientists have increased focus on the oncogenic potential of the Human Papillomavirus (HPV) and its oncogenic potential for the development of these malignancies, especially the OP malignancies. HPV is a family of over 100 viral species. Among them, HPV-16 has emerged as an etiologic factor for the development of OP-SCC.
Data from the U.S. cancer registries estimates that 71% of the OP-SCC each year are associated with HPOV infection (Senkomago, et al., 2019). There are some cases of OC or OP malignancies which cannot be assigned an etiologic factor.
Treatment and oral health considerations
Treatment of OC and OP malignancies reflect the stages at which these lesions are diagnosed. Unfortunately, many of these malignancies are diagnosed at advanced stages. These require proportionately more invasive surgical procedures, which are usually combined with post-surgical radiation. Chemotherapy may be used pre-surgically to reduce the size of the malignancy.
Chemotherapy can cause transient but dire adverse effects for the oral cavity and oropharyngeal region. Chemotherapeutic agents are non-selective and have a low margin of safety. They target actively dividing cells which are malignant, but they also affect those of the oral cavity which actively divide to replenish the surface layer.
When the chemotherapeutic agents disrupt this process of renewal, the outer layer becomes ulcerated with the lesions known as mucositis. Chemotherapeutic agents also disrupt the formation of the following cell types in human blood:
- Leukocytes (white blood cells)
- Erythrocytes (red blood cells)
- Thrombocytes (platelets)
Leukocytes are the foundation of the immune system. Their diminished production will leave a patient prone to the development of opportunistic oral infections. Erythrocytes perform the essential function of delivering oxygen to the tissues. A decrease in erythrocyte production will cause fatigue and anemia while a decrease in platelets will challenge the ability to obtain hemostasis.
Radiation treatment post-surgically is designed to destroy any stray malignant cells that have not been eradicated through surgery or chemotherapy. This treatment modality can also cause mucositis and permanent damage to the salivary glands if they are in the zone of radiation. This can cause xerostomia (dry mouth), which can cause several long-term problems within the oral cavity.
Radiation treatment can also cause the necrosis of bone (osteoradionecrosis). This can cause necrotic segments of bone to emerge through the oral tissues long after radiation treatment has been completed.
Dental pre-treatment for oral cancer patients
Chemotherapy and radiation therapy can have short-term and long-term adverse effects for the oral cavity and the oropharyngeal region. Dental pre-treatment prior to the actual surgical, chemotherapeutic or radiation therapy involves examining, diagnosing, and treating teeth that could cause severe problems during these treatment regimens. Many dental problems, such as teeth with necrotic, carious lesions, teeth with periodontal defects, or impacted wisdom teeth are asymptomatic in the presence of an intact immune system.
However, these same problems can cause local, regional, and even systemic infections (sepsis) when chemotherapy causes a depletion of the leukocytic series. Dental pre-treatment involves diagnosing odontogenic problems when they are present and restoring teeth with carious lesions, treating necrotic teeth with either endodontic (root canal therapy) or extractions.
It also involves treating periodontal problems with various modes of periodontal therapy or extractions. This is a special concern for patients who have not seen a dentist in a long time and that may have dental pathology of which they are unaware.
Summary
This article has highlighted some basic concepts which are associated with OC and OP malignancies and should be considered as only a very brief introduction to a very complex topic. All dental clinicians must perform screenings on their patients for these malignancies as early detection will provide the patient with the best opportunity for long-term survival and to maintain an optimum quality of life.
References
- The American Dental Association. Cancer (Head and Neck). Last Updated September 30, 2022. https://www.ada.org>research>oral-health-topics>c…
- Siegel RL, Miller KD, Fuchs HE, Jemal A. Cancer Statistics 2022. CA: A Cancer Journal for Clinicians 2022;72(1):7-33.
- The Oral Cancer Foundation. CDC Oral cancer Background Papers. © 2023 https://oralcancerfoundation.org>cdc
- Senkomago V, Henley SJ, Thomas CC, et al. Human papillomavirus-attributable cancers-United States,2012-2016. MMWR Morb Morta Wkly Rep 2019;68(33):724-28.
