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.

The basis of deciding the T stage depends on physical examination and imaging of the tumor.

These aggressive tumors are generally diagnosed at advanced stages and survival is generally shorter. The prognosis of SRCC and its chemosensitivity with specific regimens are still controversial as SRCC is not specifically identified in most studies and its poor prognosis may be due to its more advanced stage. One study suggests that its dismal prognosis seems to be caused by its intrinsic tumor biology, suggesting an area for further research.

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.

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.

Primary signet-ring cell carcinoma of the urinary bladder is extremely rare and patient survival is very poor and occurs mainly in men ages 38 to 83. However, one such patient treated with a radical cystectomy followed by combined S-1 and Cisplatin adjuvant chemotherapy did demonstrate promising long-term survival of 90 months.

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.

LCIS (lobular neoplasia is considered pre-cancerous) is an indicator (marker) identifying women with an increased risk of developing invasive breast cancer. This risk extends more than 20 years. Most of the risk relates to subsequent invasive ductal carcinoma rather than to invasive lobular carcinoma.

While older studies have shown that the increased risk is equal for both breasts, a more recent study suggests that the ipsilateral (same side) breast may be at greater risk.

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.

In the United States screening is typically recommended between the age of 50 and 75 years. For those between 76 and 85 years of age the decision to screen should be individualized. A number of screening methods can be used including stool based tests every 3 years, sigmoidoscopy every 5 years and colonoscopy every 10 years. For those at high risk, screenings usually begin at around 40. It is unclear which of these two methods is better. Colonoscopy may find more cancers in the first part of the colon but is associated with greater cost and more complications. For people with average risk who have had a high-quality colonoscopy with normal results, the American Gastroenterological Association does not recommend any type of screening in the 10 years following the colonoscopy. For people over 75 or those with a life expectancy of less than 10 years, screening is not recommended. It takes about 10 years after screening for one out of a 1000 people to benefit.

In Canada, among those 50 to 75 at normal risk, fecal immunochemical testing or FOBT is recommended every two years or sigmoidoscopy every 10 years. Colonoscopy is less preferred.

Some countries have national colorectal screening programs which offer FOBT screening for all adults within a certain age group, typically starting between age 50 and 60. Examples of countries with organised screening include the United Kingdom, Australia and the Netherlands.

LCIS may be treated with close clinical follow-up and mammographic screening, tamoxifen or related hormone controlling drugs to reduce the risk of developing cancer, or bilateral prophylactic mastectomy. Some surgeons consider bilateral prophylactic mastectomy to be overly aggressive treatment except for certain high-risk cases.

Aspirin and celecoxib appear to decrease the risk of colorectal cancer in those at high risk. Aspirin is recommended in those who are 50 to 60 years old, do not have an increased risk of bleeding, and are at risk for cardiovascular disease to prevent colorectal cancer. It is not recommended in those at average risk. There is tentative evidence for calcium supplementation, but it is not sufficient to make a recommendation. Vitamin D intake and blood levels are associated with a lower risk of colon cancer.

HGPIN in isolation does not require treatment. In prostate biopsies it is not predictive of prostate cancer in one year if the prostate was well-sampled, i.e. if there were 8 or more cores.

The exact timing of repeat biopsies remains an area of controversy, as the time required for, and probability of HGPIN transformations to prostate cancer are not well understood.

HGPIN is diagnosed from tissue by a pathologist, which may come from:

- a needle biopsy taken via the rectum and,

- surgical removal of prostate tissue:

- transurethral resection of the prostate - removal of extra prostate tissue to improve urination (a treatment for benign prostatic hyperplasia),

- radical prostatectomy - complete removal of prostate and seminal vesicles (a treatment for prostate cancer).

Blood tests for prostate specific antigen (PSA), digital rectal examination, ultrasound scanning of the prostate via the rectum, fine needle aspiration or medical imaging studies (such as magnetic resonance imaging) are "not" useful for diagnosing HGPIN.

This disease is often discovered during surgery for other conditions, e.g., hernia repair, following which an experienced pathologist can confirm the diagnosis. Advanced stages may present as tumors palpable on the abdomen or distention of the belly ("jelly belly" is sometimes used as a slang term for the condition). Due to the rarity of this disease, it is important to obtain an accurate diagnosis so that appropriate treatment may be obtained from a surgical oncologist who specializes in appendix cancer. Diagnostic tests may include CT scans, examination of tissue samples obtained through laparoscopy, and the evaluation of tumor markers. In most cases a colonoscopy is unsuitable as a diagnostic tool because in most cases appendix cancer invades the abdominal cavity but not the colon (however, spread inside the colon is occasionally reported). PET scans may be used to evaluate high-grade mucinous adenocarcinoma, but this test is not reliable for detecting low-grade tumors because those do not take up the dye which shows up on scans. New MRI procedures are being developed for disease monitoring, but standard MRIs are not typically used as a diagnostic tool. Diagnosis is confirmed through pathology.

Adenocarcinoma of the lung tends to stain mucin positive as it is derived from the mucus-producing glands of the lungs. Similar to other adenocarcinoma, if this tumor is well differentiated (low grade) it will resemble the normal glandular structure. Poorly differentiated adenocarcinoma will not resemble the normal glands (high grade) and will be detected by seeing that they stain positive for mucin (which the glands produce). Adenocarcinoma can also be distinguished by staining for TTF-1, a cell marker for adenocarcinoma.

To reveal the adenocarcinomatous lineage of the solid variant, demonstration of intracellular mucin production may be performed. Foci of squamous metaplasia and dysplasia may be present in the epithelium proximal to adenocarcinomas, but these are not the precursor lesions for this tumor. Rather, the precursor of peripheral adenocarcinomas has been termed "atypical adenomatous hyperplasia" (AAH). Microscopically, AAH is a well-demarcated focus of epithelial proliferation, containing cuboidal to low-columnar cells resembling club cells or type II pneumocytes. These demonstrate various degrees of cytologic atypia, including hyperchromasia, pleomorphism, prominent nucleoli. However, the atypia is not to the extent as seen in frank adenocarcinomas. Lesions of AAH are monoclonal, and they share many of the molecular aberrations (like KRAS mutations) that are associated with adenocarcinomas.

Early stage disease is treated surgically. Targeted therapy is available for lung adenocarcinomas with certain mutations. Crizotinib is effective in tumors with fusions involving ALK or ROS1, whereas gefitinib, erlotinib, and afatinib are used in patients whose tumors have mutations in EGFR.

Human papillomavirus infection (HPV) has been associated with SCC of the oropharynx, lung, fingers and anogenital region.

Treatment is variable, both due to its rarity and to its frequently slow-growing nature. Treatment ranges from watchful waiting to debulking and hyperthermic intraperitoneal chemotherapy (HIPEC, also called intraperitoneal hyperthermic chemotherapy, IPHC) with cytoreductive surgery.

Since Krukenberg tumors are secondary (metastatic), management might logically be driven by identifying and treating the primary cancer. The optimal treatment of Krukenberg tumors is unclear. The role of surgical resection has not been adequately addressed but if metastasis is limited to the ovaries, surgery may improve survival. The role of chemotherapy and/or radiotherapy is uncertain but may sometimes be beneficial.

Although reliable and comprehensive incidence statistics are nonexistent, LCLC-RP is a rare tumor, with only a few hundred cases described in the scientific literature to date. LCLC's made up about 10% of lung cancers in most historical series, equating to approximately 22,000 cases per year in the U.S. Of these LCLC cases, it is estimated that about 1% will eventually develop the rhabdoid phenotype during tumor evolution and progression. In one large series of 902 surgically resected lung cancers, only 3 cases (0.3%) were diagnosed as LCLC-RP. In another highly selected series of large-cell lung carcinoma cases, only 4 of 45 tumors (9%) were diagnosed as the rhabdoid phenotype using the 10% criterion, but another 10 (22%) had at least some rhabdoid cell formation. It appears likely, therefore, that LCLC-RP probably comprises between 0.1% and 1.0% of all lung malignancies.

Similar to nearly all variants of lung carcinoma, large cell lung carcinoma with rhabdoid phenotype appears to be highly related to tobacco smoking. It also appears to be significantly more common in males than in females.

Ninety percent of cases of head and neck cancer (cancer of the mouth, nasal cavity, nasopharynx, throat and associated structures) are due to squamous cell carcinoma.

LCLC-RP are considered to be especially aggressive tumors with a dismal prognosis. Many published cases have shown short survival times after diagnosis. Some studies suggest that, as the proportion of rhabdoid cells in the tumor increases, the prognosis tends to worsen, although this is most pronounced when the proportion of rhabdoid cells exceeds 5%. With regard to "parent" neoplasms other than LCLC, adenocarcinomas with rhabdoid features have been reported to have worse prognoses than adenocarcinomas without rhabdoid features, although an "adenocarcinoma with rhabdoid phenotype" tumor variant has not been specifically recognized as a distinct entity under the WHO-2004 classification system.

Interestingly, there are case reports of rhabdoid carcinomas recurring after unusually long periods, which is unusual for a fast-growing, aggressive tumor type. One report described a very early stage patient whose tumor recurred 6 years after initial treatment. Although rapidly progressive, fulminant courses seem to be the rule in this entity, long-term survival has also been noted, even post-metastectomy in late stage, distant metastatic disease.

There has been debate over the exact mechanism of metastasis of the tumor cells from the stomach, appendix or colon to the ovaries. Classically it was thought that direct seeding across the abdominal cavity accounted for the spread of this tumor, but spread by way of the lymphatic is considered more likely. The average age of diagnosis of Krukenberg tumors may partly relate to the relatively increased vascularity of the ovaries.

Microscopically, Krukenberg tumors are often characterized by mucin-secreting signet-ring cells in the tissue of the ovary; when the primary tumor is discovered, the same signet-ring cells are typically found. However, other microscopic features can predominate. Krukenberg tumors are most commonly metastases from gastric cancer, particularly adenocarcinoma, or breast cancer particularly invasive lobular breast carcinoma, but they can arise in the appendix, colon, small intestine, rectum, gallbladder, and urinary bladder or gallbladder, biliary tract, pancreas, ampulla of Vater or uterine cervix.

Immunohistochemistry may help in diagnosing Krukenberg tumors from primary ovarian neoplasms but needs to be applied with discretion. For example, tumors that are immunoreactive to CEA or cytokeratin 20 (CK20) and negative for cytokeratin 7 (CK7) may be more likely to be of colorectal origin.

"FLCN" mutations are detected by sequencing in 88% of probands with Birt–Hogg–Dubé syndrome. This means that some people with the clinical diagnosis have mutations that are not detectable by current technology, or that mutations in another currently unknown gene could be responsible for a minority of cases. In addition, amplifications and deletions in exonic regions are also tested. Genetic testing can be useful to confirm the clinical diagnosis of and to provide a means of determining other at-risk individuals in a family even if they have not yet developed BHD symptoms.