Avoidance of recognised risk factors (as described above) is the single most effective form of prevention. Regular dental examinations may identify pre-cancerous lesions in the oral cavity.

When diagnosed early, oral, head and neck cancers can be treated more easily and the chances of survival increase tremendously. As of 2017 it was not known if existing HPV vaccines can help prevent head and neck cancer.

Diagnosis is made by the doctor on the basis of a medical history, physical examination, and special investigations which may include a chest x-ray, CT or MRI scans, and tissue biopsy. The examination of the larynx requires some expertise, which may require specialist referral.

The physical exam includes a systematic examination of the whole patient to assess general health and to look for signs of associated conditions and metastatic disease. The neck and supraclavicular fossa are palpated to feel for cervical adenopathy, other masses, and laryngeal crepitus. The oral cavity and oropharynx are examined under direct vision. The larynx may be examined by indirect laryngoscopy using a small angled mirror with a long handle (akin to a dentist's mirror) and a strong light. Indirect laryngoscopy can be highly effective, but requires skill and practice for consistent results. For this reason, many specialist clinics now use fibre-optic nasal endoscopy where a thin and flexible endoscope, inserted through the nostril, is used to clearly visualise the entire pharynx and larynx. Nasal endoscopy is a quick and easy procedure performed in clinic. Local anaesthetic spray may be used.

If there is a suspicion of cancer, biopsy is performed, usually under general anaesthetic. This provides histological proof of cancer type and grade. If the lesion appears to be small and well localised, the surgeon may undertake excision biopsy, where an attempt is made to completely remove the tumour at the time of first biopsy. In this situation, the pathologist will not only be able to confirm the diagnosis, but can also comment on the completeness of excision, i.e., whether the tumour has been completely removed. A full endoscopic examination of the larynx, trachea, and esophagus is often performed at the time of biopsy.

For small glottic tumours further imaging may be unnecessary. In most cases, tumour staging is completed by scanning the head and neck region to assess the local extent of the tumour and any pathologically enlarged cervical lymph nodes.

The final management plan will depend on the site, stage (tumour size, nodal spread, distant metastasis), and histological type. The overall health and wishes of the patient must also be taken into account. A prognostic multigene classifier has been shown to be potentially useful for the distinction of laryngeal cancer of low or high risk of recurrence and might influence the treatment choice in future.

The US Preventive Services Task Force (USPSTF) in 2013 stated evidence was insufficient to determine the balance of benefits and harms of screening for oral cancer in adults without symptoms by primary care providers. The American Academy of Family Physicians comes to similar conclusions while the American Cancer Society recommends that adults over 20 years who have periodic health examinations should have the oral cavity examined for cancer. The American Dental Association recommends that providers remain alert for signs of cancer during routine examinations.

There are a variety of screening devices, however, there is no evidence that routine use of these devices in general dental practice is helpful. However, there are compelling reasons to be concerned about the risk of harm this device may cause if routinely used in general practice. Such harms include false positives, unnecessary surgical biopsies and a financial burden on the patient.

Early diagnosis of oral cancer patients would decrease mortality and help to improve treatment. Oral surgeons and dentists can diagnose these patients in the early stages. Health providers, dentists, and oral surgeons shall have high knowledge and awareness that would help them to provide better diagnosis for oral cancer patients. An examination of the mouth by the health care provider, dentist, oral surgeons shows a visible and/or palpable (can be felt) lesion of the lip, tongue, or other mouth area. The lateral/ventral sides of the tongue are the most common sites for intraoral SCC. As the tumor enlarges, it may become an ulcer and bleed. Speech/talking difficulties, chewing problems, or swallowing difficulties may develop. A feeding tube is often necessary to maintain adequate nutrition. This can sometimes become permanent as eating difficulties can include the inability to swallow even a sip of water. The doctor can order some special investigations which may include a chest x-ray, CT or MRI scans, and tissue biopsy.

While a dentist, physician or other health professional may suspect a particular lesion is malignant, there is no way to tell by looking alone - since benign and malignant lesions may look identical to the eye. A non-invasive brush biopsy (BrushTest) can be performed to rule out the presence of dysplasia (pre-cancer) and cancer on areas of the mouth that exhibit an unexplained color variation or lesion. The only definitive method for determining if cancerous or precancerous cells are present is through biopsy and microscopic evaluation of the cells in the removed sample. A tissue biopsy, whether of the tongue or other oral tissues and microscopic examination of the lesion confirm the diagnosis of oral cancer or precancer.

The presence of HPV within the tumour has been realised to be an important factor for predicting survival since the 1990s. Tumor HPV status is strongly associated with positive therapeutic response and survival compared with HPV-negative cancer, independent of the treatment modality chosen and even after adjustment for stage. While HPV+OPC patients have a number of favourable demographic features compared to HPV-OPC patients, such differences account for only about ten per cent of the survival difference seen between the two groups. Response rates of over 80% are reported in HPV+ cancer and three-year progression free survival has been reported as 75–82% and 45–57%, respectively, for HPV+ and HPV- cancer, and improving over increasing time. It is likely that HPV+OPC is inherently less maligant than HPV-OPC, since patients treated by surgery alone have a better survival after adjustment for stage. In one study, less than 50% of patients with HPV-OPC were still alive after five years, compared to more than 70% with HPV+OPC and an equivalent stage and disease burden.

In RTOG clinical trial 0129, in which all patients with advanced disease received radiation and chemotherapy, a retrospective analysis (recursive-partitioning analysis, or RPA) at three years identified three risk groups for survival (low, intermediate, and high) based on HPV status, smoking, T stage and N stage ("see" Ang et al., Fig. 2). HPV status was the major determinant of survival, followed by smoking history and stage. 64% were HPV+ and all were in the low and intermediate risk group, with all non-smoking HPV+ patients in the low risk group. 82% of the HPV+ patients were alive at three years compared to 57% of the HPV- patients, a 58% reduction in the risk of death. Locoregional failure is also lower in HPV+, being 14% compared to 35% for HPV-. HPV positivity confers a 50–60% lower risk of disease progression and death, but the use of tobacco is an independently negative prognostic factor. A pooled analysis of HPV+OPC and HPV-OPC patients with disease progression in RTOG trials 0129 and 0522 showed that although less HPV+OPC experienced disease progression (23 v. 40%), the median time to disease progression following treatment was similar (8 months). The majority (65%) of recurrences in both groups occurred within the first year after treatment and were locoregional. HPV+ did not reduce the rate of metastases (about 45% of patients experiencing progression), which are predominantly to the lungs (70%), although some studies have reported a lower rate. with 3-year distant recurrence rates of about 10% for patients treated with primary radiation or chemoradiation. Even if recurrence or metastases occur, HPV positivity still confers an advantage.

By contrast tobacco usage is an independently negative prognostic factor, with decreased response to therapy, increased disease recurrence rates and decreased survival. The negative effects of smoking, increases with amount smoked, particularly

if greater than 10 pack-years. For patients such as those treated on RTOG 0129 with primary chemoradiation, detailed nomograms have been derived from that dataset combined with RTOG 0522, enabling prediction of outcome based on a large number of variables. For instance, a 71 year old married non-smoking high school graduate with a performance status (PS) of 0, and no weight loss or anaemia and a T3N1 HPV+OPC would expect to have a progression-free survival of 92% at 2 years and 88% at 5 years. A 60 year old unmarried nonsmoking high school graduate with a PS of 1, weight loss and anaemia and a T4N2 HPV+OPC would expect to have a survival of 70% at two years and 48% at five years. Less detailed information is available for those treated primarily with surgery, for whom less patients are available, as well as low rates of recurrence (7–10%), but features that have traditionally been useful in predicting prognosis in other head and neck cancers, appear to be less useful in HPV+OPC. These patients are frequently stratified into three risk groups:

- Low risk: No adverse pathological features

- Intermediate risk: T3–T4 primary, perineural or lymphovascular invasion, N2 (AJCC 7)

- High risk: Positive margins, ECE

HPV+OPC patients are less likely to develop other cancers, compared to other head and neck cancer patients. A possible explanation for the favourable impact of HPV+ is "the lower probability of occurrence of 11q13 gene amplification, which is considered to be a factor underlying faster and more frequent recurrence of the disease" Presence of TP53 mutations, a marker for HPV- OPC, is associated with worse prognosis. High grade of p16 staining is thought to be better than HPV PCR analysis in predicting radiotherapy response.

People with HPV-mediated oropharyngeal cancer tend to have higher survival rates. The prognosis for people with oropharyngeal cancer depends on the age and health of the person and the stage of the disease. It is important for people with oropharyngeal cancer to have follow-up exams for the rest of their lives, as cancer can occur in nearby areas. In addition, it is important to eliminate risk factors such as smoking and drinking alcohol, which increase the risk for second cancers.

In some situations HPV+OPC may present with cervical lymph nodes but no evident disease of a primary tumour (T0 N1-3) and is therefore classed as Squamous Cell Carcinoma of Unknown Primary Origin. The lack of any such evidence of a primary tumour occurs in 2-4% of patients presenting with metastatic cancer in the cervical nodes. The incidence of HPV positivity is increasing at a similar rate to that seen in OPC. In such situations, resection of the lingual and palatine tonsils, together with neck dissection may be diagnostic and constitute sufficient intervention, since recurrence rates are low.

The first step to diagnosing tonsil carcinoma is to obtain an accurate history from the patient. The physician will also examine the patient for any indicative physical signs. A few tests then, maybe conducted depending on the progress of the disease or if the doctor feels the need for. The tests include:

Fine needle aspiration, blood tests, MRI, x-rays and PET scan.

There are several ways to diagnose Hypopharyngeal Cancer.

- Physical Examination:

The doctor checks for swollen lymph nodes and may look down the patient’s throat with a long handled mirror.

- Endoscopy, Esophagoscopy, or Bronchoscopy:

Inserted into the nose or mouth of the patient, this a thin, lighted tube that allows the doctor to see farther down the throat, into the esophagus or into the trachea.

- Biopsy:

This is a small tissue sample that can be acquired during an endosopy, esophagoscopy, or bronchoscopy. The tissue is analyzed for the presences of cancer cells.

- CT scan or MRI:

These tests will give doctors a detailed picture of any abnormalities in the body. For a CT scan, the patient often swallows a dye that coats the throat and provides a better image. An MRI is a better tool if the patient is pregnant because the test uses no radiation.

Adenocarcinoma is a cancer of epithelial tissue that has glandular characteristics. Several head and neck cancers are adenocarcinomas (either of intestinal or non-intestinal cell-type).

The staging of a tumor mass is based on TNM staging.

T staging is the based on the tumor mass. The N staging is based on the extent of spread of cancer to the lymph nodes. Finally, the M stage indicates if the cancer has spread beyond the head and neck or not.

Cancer has spread to other parts of the body; the tumor may be any size and may have spread to lymph nodes.

Staging cancer is a way of marking the cancer’s progression and is measured on a 0 to 4 (IV) scale. To determine

each stage, smaller categories must be defined first: T. N. M. (tumor, lymph nodes, and metastasis). These were developed by the American Joint Committee on Cancer.

Smoking is the most important risk factor for laryngeal cancer. Death from laryngeal cancer is 20 times more likely for heaviest smokers than for nonsmokers. Heavy chronic consumption of alcohol, particularly alcoholic spirits, is also significant. When combined, these two factors appear to have a synergistic effect.

Some other quoted risk factors are likely, in part, to be related to prolonged alcohol and tobacco consumption. These include low socioeconomic status, male sex, and age greater than 55 years.

People with a history of head and neck cancer are known to be at higher risk (about 25%) of developing a second cancer of the head, neck, or lung. This is mainly because in a significant proportion of these patients, the aerodigestive tract and lung epithelium have been exposed chronically to the carcinogenic effects of alcohol and tobacco. In this situation, a field change effect may occur, where the epithelial tissues start to become diffusely dysplastic with a reduced threshold for malignant change. This risk may be reduced by quitting alcohol and tobacco.

Staging of nasopharyngeal carcinoma is based on clinical and radiologic examination. Most patients present with Stage III or IV disease.

Stage I is a small tumor confined to nasopharynx.

Stage II is a tumor extending in the local area, or that with any evidence of limited neck (nodal) disease.

Stage III is a large tumor with or without neck disease, or a tumor with bilateral neck disease.

Stage IV is a large tumor involving intracranial or infratemporal regions, an extensive neck disease, and/or any distant metastasis.

Head and neck cancers are malignant neoplasms that arise in the head and region which comprises nasal cavity, paranasal sinuses, oral cavity, salivary glands, pharynx, and larynx. Majority of head and neck cancers histologically belong to squamous cell type and hence they are categorized as Head and Neck Squamous Cell Carcinoma (abbreviated as HNSCC)[Forastiere AA, 2003]. HNSCC are the 6th most common cancers worldwide and 3rd most common cancers in developing world. They account for ~ 5% of all malignancies worldwide (Ferlay J, 2010) and 3% of all malignancies in the United States (Siegel R, 2014).

Risk factors include tobacco consumption (chewing or smoking), alcohol consumption, Epstein-Barr virus (EBV) infection, human papilloma virus (HPV; esp. HPV 16, 18) infection, betel nut chewing, wood dust exposures, consumption of certain salted fish and others (NCI Factsheet, 2013). EBV infection has been specifically associated with nasopharyngeal cancer. Reverse smoking was considered as a risk factor for oral cancer. Interestingly, "Cis-retinoic acid" (i.e. supplements of retinoic acid) intake may increase the risk of HNSCC in active smokers. Low consumption of fruits and vegetables was associated with higher incidence of HNSCC.

HNSCC classification: Based on the HPV infection status, head and neck cancers are classified into HPV-positive and HPV-negative categories. So far, this is the only available molecular classification. Majority (>50%) of oral cancers are HPV-positive in the U.S. HPV-positive oral cancers are widely prevalent in younger patients and are associated with multiple sexual partners and oral sexual practices. HPV-positive cancers have better prognosis, especially for nonsmokers as compared to HPV-negative cancers.

Staging and grading of HNSCC: HNSCC are classified according to the tumor-node-metastasis (TNM) system of American Joint Committee on cancer. TNM staging system for HNSCC are discussed else where.

Symptoms include lump or sore, sore throat, hoarse of voice, difficulty in swallowing etc (NCI Factsheet, 2013).

Treatment for HNSCC is predominantly based on the stage of the disease. Factors such as patient fitness, baseline swallow, airway functional status, and others are considered before determining the treatment plan. Standard of care for HNSCC includes one or combination of the following: surgery, radiation, chemotherapeutic agents such as Cisplatin, 5-Flurouracil (5-FU) etc. Molecularly targeted therapies were developed since the discovery of role of epidermal growth factor receptor (EGFR) signaling in HNSCC development, progression and prognosis. These targeted therapies include monoclonal antibodies (such as cetuximab, panitumumab etc.) and tyrosine kinase inhibitors (such as erlotinib, gefitinib, etc.). Among these EGFR-targeting agents, only cetuximab has been approved by FDA in 2006 for HNSCC treatment.

Ninety percent (MacMillan, 2015) of cases of head and neck cancer (cancer of the mouth, nasal cavity, nasopharynx, throat and associated structures) are due to squamous cell carcinoma. Symptoms may include a poorly healing mouth ulcer, a hoarse voice or other persistent problems in the area. Treatment is usually with surgery (which may be extensive) and radiotherapy. Risk factors include smoking, alcohol consumption and hematopoietic stem cell transplantation (Elad S, Zadik Y, Zeevi I, et al., 2010, pp. 1243–1244). In addition, recent studies show that about 25% of mouth and 35% of throat cancers are associated with HPV. The 5 year disease free survival rate for HPV positive cancer is significantly higher when appropriately treated with surgery, radiation and chemotherapy as compared to non-HPV positive cancer, substantiated by multiple studies including research conducted by Maura Gillison, "et al." of Johns Hopkins Sidney Kimmel Cancer Center.

Diagnosis is confirmed via biopsy of the tissue(s) suspected to be affected by SCC. For the skin, look under skin biopsy.

The pathological appearance of a squamous cell cancer varies with the depth of the biopsy. For that reason, a biopsy including the subcutaneous tissue and basalar epithelium, to the surface is necessary for correct diagnosis. The performance of a shave biopsy (see skin biopsy) might not acquire enough information for a diagnosis. An inadequate biopsy might be read as actinic keratosis with follicular involvement. A deeper biopsy down to the dermis or subcutaneous tissue might reveal the true cancer. An excision biopsy is ideal, but not practical in most cases. An incisional or punch biopsy is preferred. A shave biopsy is least ideal, especially if only the superficial portion is acquired.

The long-term outcome of squamous cell carcinomas is dependent upon several factors: the sub-type of the carcinoma, available treatments, location(s) and severity, and various patient health-related variables (accompanying diseases, age, etc.). Generally, the long-term outcome is positive, as less than 4% of Squamous cell carcinoma cases are at risk of metastasis. Some particular forms of squamous cell carcinomas have a higher mortality rate. One study found squamous cell carcinoma of the penis had a much greater rate of mortality than some other forms of squamous cell carcinoma, that is, about 23%, although this relatively high mortality rate may be associated with possibly latent diagnosis of the disease due to patients avoiding genital exams until the symptoms are debilitating, or refusal to submit to a possibly scarring operation upon the genitalia. Squamous cell carcinoma occurring in the organ transplant population is also associated with a higher risk of mortality.

Antibodies may be used to determine the expression of protein markers on the surface of cancer cells. Often the expression of these antigens is similar to the tissue that the cancer grew from, so immunohistochemical testing sometimes helps to identify the source of the cancer. Individual tests often do not provide definitive answers, but sometimes patterns may be observed, suggesting a particular site of origin (e.g. lung, colon, etc.). Immunohistochemical testing suggests a single source of cancer origin in about one in four cases of CUP. However, there is a lack of definitive research data showing that treatment guided by information from immunohistochemical testing improves outcomes or long-term prognosis.

Nasopharyngeal carcinoma can be treated by surgery, by chemotherapy, or by radiotherapy. The expression of EBV latent proteins within undifferentiated nasopharyngeal carcinoma can be potentially exploited for immune-based therapies.

Definitive diagnosis of Merkel cell carcinoma (MCC) requires examination of biopsy tissue. An ideal biopsy specimen is either a punch biopsy or a full-thickness incisional biopsy of the skin including full-thickness dermis and subcutaneous fat. In addition to standard examination under light microscopy, immunohistochemistry (IHC) is also generally required to differentiate MCC from other morphologically similar tumors such as small cell lung cancer, the small cell variant of melanoma, various cutaneous leukemic/lymphoid neoplasms, and Ewing's sarcoma. Similarly, most experts recommend longitudinal imaging of the chest, typically a CT scan, to rule out that the possibility that the skin lesion is a cutaneous metastasis of an underlying small cell carcinoma of the lung.

A research article from 1923 notes that the “average duration of life” in those with Kangri cancer is about fifteen months, though there have been records of people dying within one year and living for more than twenty years with Kangri cancer. Updated life expectancy is not found in more recent scientific publications.

However, in 2013, it was noted that the progression from erythema ab igne to squamous cell carcinoma, manifesting as Kangri cancer, was between one to two decades.

It has been reported that about one-third to one-half of patients with Kangri cancer show metastasis to local lymph nodes.

In the treatment of Kangri cancer, surgery is, most often, the first-line course of action to remove the primary tumor.

An important anatomic landmark in anal cancer is the pectinate line (dentate line), which is located about 1–2 cm from the anal verge (where the anal mucosa of the anal canal becomes skin). Anal cancers located above this line (towards the head) are more likely to be carcinomas, whilst those located below (towards the feet) are more likely to be squamous cell carcinomas that may ulcerate. Anal cancer is strongly associated with ulcerative colitis and the sexually transmissible infections HPV and HIV. Anal cancer may be a cause of constipation or tenesmus, or may be felt as a palpable mass, although it may occasionally present as an ulcerative form.

Anal cancer is investigated by biopsy and may be treated by excision and radiotherapy, or with external beam radiotherapy and adjunctive chemotherapy. The five-year survival rate with the latter procedure is above 70%.

Colorectal cancer is a disease of old age: It typically originates in the secretory cells lining the gut, and risk factors include diets low in vegetable fibre and high in fat. If a younger person gets such a cancer, it is often associated with hereditary syndromes like Peutz-Jegher's, hereditary nonpolyposis colorectal cancer or familial adenomatous polyposis. Colorectal cancer can be detected through the bleeding of a polyp, colicky bowel pain, a bowel obstruction or the biopsy of a polyp at a screening colonoscopy. A constant feeling of having to go to the toilet or anemia might also point to this kind of cancer.

Use of a colonoscope can find these cancers, and a biopsy can reveal the extent of the involvement of the bowel wall. Removal of a section of the colon is necessary for treatment, with or without chemotherapy. Colorectal cancer has a comparatively good prognosis when detected early.