Oral cancer is a chronic pathological process that requires several years or even ten years of precancerous process of oral mucosa before it enters into typical or obvious cancerous lesions. It is mostly found in superficial parts of the oral cavity, which is beneficial to doctors and patients for direct examination and detection, so as to facilitate early diagnosis and timely prevention. At present, the oral medical profession believes that oral mucosal leukoplakia, oral mucosal erythema, lichen planus and submucosal fibroplasia should be regarded as oral precancerous lesions. Among them, the prevalence of oral mucosal leukoplakia is the highest and the possibility of carcinoma is also higher. After years of research, it is believed that the occurrence of oral cancer is related to many factors.
1.Long-term addiction to tobacco and alcohol
Most oral cancer patients have a long history of smoking and drinking, while oral cancer in non-smokers and non-drinkers is rare. In 1982, Trivandrum Cancer Center in India treated 234 cases of buccal mucosa cancer, 98% of which had a history of chewing tobacco and tobacco lumps. In some parts of the world, such as Sri Lanka, India, Myanmar, Malaysia, etc., people have the habit of chewing betel nut or “nas”.
Chewing betel nut and other mixtures can cause the oral mucosa epithelial basal cell division activity increased, so that the incidence of oral cancer increased. American Keller data show that the incidence of oral cancer in smokers who do not drink alcohol or alcoholics who do not smoke is 2.43 times and 2.33 times, respectively, while the incidence of smokers and alcoholics is 15.5 times that of non-smokers and non-drinkers. Alcohol itself has not been shown to be carcinogenic, but it has a pro-carcinogenic effect. Alcohol may act as a solvent for carcinogens and promote carcinogens to enter the oral mucosa.
2.Poor oral hygiene
Poor oral hygiene creates conditions for bacteria or mold to breed and multiply in the oral cavity, thus facilitating the formation of nitrosamines and their precursors. Coupled with stomatitis, some cells are in proliferative state and more sensitive to carcinogens, so all these reasons may promote the occurrence of oral cancer.
3.Long-term stimulation of foreign body
Tooth roots or sharp tooth tips, unsuitable dentures stimulate oral mucosa for a long time, resulting in chronic ulcers and even cancer.
4.Malnutrition teeth
Some people think that it is related to the lack of vitamin A, because vitamin A has the function of maintaining the normal structure and function of epithelium, and vitamin A deficiency can cause the thickening of oral mucosa epithelium and hyperkeratosis, which is related to the occurrence of oral cancer. Demographic studies have shown a high incidence of oral cancer in countries with low vitamin A intake. Vitamin C deficiency has not yet been shown to be associated with oral cancer. It is also thought to be related to insufficient intake of micronutrients, such as low iron content in food. Inadequate intake of total protein and animal protein may be associated with oral cancer. Zinc is an indispensable element for the growth of animal tissues, and zinc deficiency may lead to mucosal epithelial damage, creating favorable conditions for the occurrence of oral cancer.
5.White spots and erythema of mucous membrane
Silveman et al. reported 257 cases of oral mucosal leukoplakia with an average follow-up of 7.2 years, 45 cases were biopsied and confirmed to be squamous carcinoma (17.5%), which was higher than 0.13%-6% previously reported. Therefore, regardless of the duration of oral mucosal leukoplakia and its benign manifestations, long-term follow-up is needed for early detection of cancer. According to the domestic oral mucosa leukoplakia prevention and control scientific research collaboration group in 1980, the prevalence of leukoplakia in Chinese people was 10.47%. Silverman et al. also pointed out that in addition to mucosal leukoplakia, proliferative erythema is more dangerous, and its malignant change can be 4 times more than that of leukoplakia patients. Kramer et al. reported that in patients with leukoplakia of the tongue and floor of the mouth, with an average of 4.3 years, cancer accounted for 15%, and the red leukoplakia was 5 times higher than that of leukoplakia. Biopsy of red and white spots should be taken from the erythematous area as far as possible, and the positive rate of this area is higher.
6.Ultraviolet and ionizing radiation
The incidence rate of lip cancer and skin cancer is higher when outdoor workers are exposed to direct sunlight for a long time. Ionizing radiation can cause changes in DNA of genetic material, activate tumor genes and lead to cancer, both r-rays or X-rays have carcinogenic effects. In Guangdong Province, due to the widespread use of radiation therapy for nasopharyngeal cancer, the risk of second primary cancer in any part of the oral cavity in the radiation area has increased.
7.Other
Micronutrients A1 and B2, as well as micronutrient drinking, zinc and arsenic deficiency will increase the body’s sensitivity to carcinogens. In addition, chronic hepatitis, liver cirrhosis and viral infection, which cause low immunity of the body, are also related to the occurrence of oral cancer.
What are the manifestations and how to diagnose oral cancer?
Clinical manifestations.
Pain: Early oral squamous carcinoma generally has no pain or only abnormal sensation or slight tenderness, but when accompanied by lump ulcer, more obvious pain will occur, but the pain is not as intense as inflammation. Therefore, when the patient complains of pain, especially gingival pain or tongue pain, the painful area should be carefully examined for hard nodes, lumps and ulcers. If there is pain or tongue pain, the painful area should be carefully examined for hard knots, lumps and ulcers. If the above signs are present in the painful area, cancer should be highly suspected.
Among oral cancers, tongue cancer and gum cancer have more complaints of pain in the early stage. If the site of pain does not match the site of oral lumps and ulcers, it is necessary to consider the possibility of tumor spreading to other areas. Toothache can be caused by gum cancer, but it can also be caused by cancer of the buccal mucosa, hard palate, floor of the mouth or tongue cancer spreading to the gum or tongue nerve. Earache and pharyngeal pain can be symptoms of oropharyngeal cancer, or can be caused by tongue cancer invading the root of tongue or cheek, hard palate or gum, or lateral fundic cancer invading the lateral wall of pharynx backward.
2.Plaque: When oral squamous carcinoma is located in superficial surface, it may appear as superficial infiltrated plaque, which is difficult to be distinguished from white spot or hyperplastic erythema without biopsy.
3.Ulcer: ulcers often occur in oral squamous carcinoma, which typically appear as infiltrating masses with hard texture, irregularly elevated edges and uneven bases, and the ulcerated surface spreads to the whole tumor area.
4.Lumps: Oral squamous carcinoma originates from oral mucosal epithelium, and its lumps are formed by the proliferation of squamous epithelium. No matter ulcers are formed in the oral cavity or deep infiltration, the lumps formed are more superficial and cancerous lesions can always be seen on the mucosa. In addition, oral cancer mostly metastasizes to the nearby cervical lymph nodes first, sometimes the primary foci are very small or even the symptoms are not obvious, but the cervical lymph nodes have already metastasized and become larger. Therefore, if lymph nodes in the neck suddenly appear to be enlarged, the oral area should be examined carefully.
Diagnosis
Once the mass is clinically determined to be from oral cancer, the scope and depth of invasion should be further determined. Any abnormalities such as sore throat, earache, nasal congestion, nasal bleeding, difficulty in opening mouth, restricted tongue movement and pain and numbness in the trigeminal nerve area should be considered when the tumor may have invaded into the oropharynx, maxillary sinus, nasal cavity, external tongue muscle, masticatory space and mandible, so that appropriate scenic examinations can be used to further deduce the location of oral cancer.