People with Barrett's esophagus (a change in the cells lining the lower esophagus) are at much higher risk, and may receive regular endoscopic screening for the early signs of cancer. Because the benefit of screening for adenocarcinoma in people without symptoms is unclear, it is not recommended in the United States. Some areas of the world with high rates of squamous-carcinoma have screening programs.

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.

While cancer is generally considered a disease of old age, children can also develop cancer. In contrast to adults, carcinomas are exceptionally rare in children..

The two biggest risk factors for ovarian carcinoma are age and family history.

Staging of carcinoma refers to the process of combining physical/clinical examination, pathological review of cells and tissues, surgical techniques, laboratory tests, and imaging studies in a logical fashion to obtain information about the size of the neoplasm and the extent of its invasion and metastasis.

Carcinomas are usually staged with Roman numerals. In most classifications, Stage I and Stage II carcinomas are confirmed when the tumor has been found to be small and/or to have spread to local structures only. Stage III carcinomas typically have been found to have spread to regional lymph nodes, tissues, and/or organ structures, while Stage IV tumors have already metastasized through the blood to distant sites, tissues, or organs.

In some types of carcinomas, Stage 0 carcinoma has been used to describe carcinoma "in situ", and occult carcinomas detectable only via examination of sputum for malignant cells (in lung carcinomas).

In more recent staging systems, substages (a, b, c) are becoming more commonly used to better define groups of patients with similar prognosis or treatment options.

Carcinoma stage is the variable that has been most consistently and tightly linked to the prognosis of the malignancy.

The criteria for staging can differ dramatically based upon the organ system in which the tumor arises. For example, the colon and bladder cancer staging system relies on depth of invasion, staging of breast carcinoma is more dependent on the size of the tumor, and in renal carcinoma, staging is based on both the size of the tumor and the depth of the tumor invasion into the renal sinus. Carcinoma of the lung has a more complicated staging system, taking into account a number of size and anatomic variables.

The UICC/AJCC TNM systems are most often used. For some common tumors, however, classical staging methods (such as the Dukes classification for colon cancer) are still used.

Staging is based on the TNM staging system, which classifies the amount of tumor invasion (T), involvement of lymph nodes (N), and distant metastasis (M). The currently preferred classification is the 2010 AJCC staging system for cancer of the esophagus and the esophagogastric junction. To help guide clinical decision making, this system also incorporates information on cell type (ESCC, EAC, etc.), grade (degree of differentiation – an indication of the biological aggressiveness of the cancer cells), and tumor location (upper, middle, lower, or junctional).

To find the cause of symptoms, the doctor asks about the patient's medical history, does a physical exam, and may order laboratory studies. The patient may also have one or all of the following exams:

- Gastroscopic exam is the diagnostic method of choice. This involves insertion of a fibre optic camera into the stomach to visualise it.

- Upper GI series (may be called barium roentgenogram).

- Computed tomography or CT scanning of the abdomen may reveal gastric cancer. It is more useful to determine invasion into adjacent tissues or the presence of spread to local lymph nodes. Wall thickening of more than 1 cm that is focal, eccentric and enhancing favours malignancy.

In 2013, Chinese and Israeli scientists reported a successful pilot study of a breathalyzer-style breath test intended to diagnose stomach cancer by analyzing exhaled chemicals without the need for an intrusive endoscopy. A larger-scale clinical trial of this technology was completed in 2014.

Abnormal tissue seen in a gastroscope examination will be biopsied by the surgeon or gastroenterologist. This tissue is then sent to a pathologist for histological examination under a microscope to check for the presence of cancerous cells. A biopsy, with subsequent histological analysis, is the only sure way to confirm the presence of cancer cells.

Various gastroscopic modalities have been developed to increase yield of detected mucosa with a dye that accentuates the cell structure and can identify areas of dysplasia. "Endocytoscopy" involves ultra-high magnification to visualise cellular structure to better determine areas of dysplasia. Other gastroscopic modalities such as optical coherence tomography are being tested investigationally for similar applications.

A number of cutaneous conditions are associated with gastric cancer. A condition of darkened hyperplasia of the skin, frequently of the axilla and groin, known as acanthosis nigricans, is associated with intra-abdominal cancers such as gastric cancer. Other cutaneous manifestations of gastric cancer include "tripe palms" (a similar darkening hyperplasia of the skin of the palms) and the Leser-Trelat sign, which is the rapid development of skin lesions known as seborrheic keratoses.

Various blood tests may be done including a complete blood count (CBC) to check for anaemia, and a fecal occult blood test to check for blood in the stool.

Chemotherapy has relatively poor curative efficacy in SRCC patients and overall survival rates are lower compared to patients with more typical cancer pathology. SRCC cancers are usually diagnosed during the late stages of the disease, so the tumors generally spread more aggressively than non-signet cancers, making treatment challenging. In the future, case studies indicate that bone marrow metastases will likely play a larger role in the diagnosis and management of signet ring cell gastric cancer.

In SRCC of the stomach, removal of the stomach cancer is the treatment of choice. There is no combination of chemotherapy which is clearly superior to others, but most active regimens include 5-Fluorouracil (5-FU), Cisplatin, and/or Etoposide. Some newer agents, including Taxol and Gemcitabine (Gemzar) are under investigation.

In a single case study of a patient with SRCC of the bladder with recurrent metastases, the patient exhibited a treatment response to palliative FOLFOX-6 chemotherapy.

Getting rid of "H. pylori" in those who are infected decreases the risk of stomach cancer, at least in those who are Asian. A 2014 meta-analysis of observational studies found that a diet high in fruits, mushrooms, garlic, soybeans, and green onions was associated with a lower risk of stomach cancer in the Korean population. Low doses of vitamins, especially from a healthy diet, decrease the risk of stomach cancer. A previous review of antioxidant supplementation did not find supporting evidence and possibly worse outcomes.

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.

A 2009 revision of the traditional Chompret criteria for screening has been proposed:

A proband who has:

- tumor belonging to the LFS tumor spectrum - soft tissue sarcoma, osteosarcoma, pre-menopausal breast cancer, brain tumor, adrenocortical carcinoma, leukemia or lung bronchoalveolar cancer - before age 46 years;

and at least one of the following:

- at least one first or second degree relative with an LFS tumour (except breast cancer if the proband has breast cancer) before age 56 years or with multiple tumours

- a proband with multiple tumours (except multiple breast tumours), two of which belong to the LFS tumour spectrum and the first of which occurred before age 46 years

- a proband who is diagnosed with adrenocortical carcinoma or choroid plexus tumour, irrespective of family history

Genetic counseling and genetic testing are used to confirm that somebody has this gene mutation. Once such a person is identified, early and regular screenings for cancer are recommended for him or her as people with Li–Fraumeni are likely to develop another primary malignancy at a future time (57% within 30 years of diagnosis).

Cancer screening uses medical tests to detect disease in large groups of people who have no symptoms. For individuals with high risk of developing lung cancer, computed tomography (CT) screening can detect cancer and give a person options to respond to it in a way that prolongs life. This form of screening reduces the chance of death from lung cancer by an absolute amount of 0.3% (relative amount of 20%). High risk people are those age 55–74 who have smoked equivalent amount of a pack of cigarettes daily for 30 years including time within the past 15 years.

CT screening is associated with a high rate of falsely positive tests which may result in unneeded treatment. For each true positive scan there are about 19 falsely positives scans. Other concerns include radiation exposure and the cost of testing along with follow up. Research has not found two other available tests—sputum cytology or chest radiograph (CXR) screening tests—to have any benefit.

The United States Preventive Services Task Force (USPSTF) recommends yearly screening using low-dose computed tomography in those who have a total smoking history of 30 pack-years and are between 55 and 80 years old until a person has not been smoking for more than 15 years. Screening should not be done in those with other health problems that would make treatment of lung cancer if found not an option. The English National Health Service was in 2014 re-examining the evidence for screening.

Staging is a formal procedure to determine how developed the cancer is. This determines treatment options.

The American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC) recommend TNM staging, using a uniform scheme for non-small cell lung carcinoma, small-cell lung carcinoma and broncho-pulmonary carcinoid tumors. With TNM staging, the cancer is classified based on the size of the tumor and spread to lymph nodes and other organs. As the tumor grows in size and the areas affected become larger, the staging of the cancer becomes more advanced as well.

There are several components of NSCLC staging which then influence physicians' treatment strategies. The lung tumor itself is typically assessed both radiographically for overall size as well as by a pathologist under the microscope to identify specific genetic markers or to see if there has been invasion into important structures within the chest (e.g., bronchus or pleural cavity). Next, the patient's nearby lymph nodes within the chest cavity known as the mediastinum will be checked for disease involvement. Finally, the patient will be evaluated for more distant sites of metastatic disease, most typically with brain imaging and or scans of the bones.

The survival rates for stages I through IV decrease significantly due to the advancement of the disease. For stage I, the five-year survival rate is 47%, stage II is 30%, stage III is 10%, and stage IV is 1%.

Following diagnosis and histopathological analysis, the patient will usually undergo magnetic resonance imaging (MRI), ultrasonography, and a bone scan in order to determine the extent of local invasion and metastasis. Further investigational techniques may be necessary depending on tumor sites. A parameningeal presentation of RMS will often require a lumbar puncture to rule out metastasis to the meninges. A paratesticular presentation will often require an abdominal CT to rule out local lymph node involvement, and so on. Patient outcomes are most strongly tied to the extent of the disease, so it is important to map its presence in the body as soon as possible in order to decide on a treatment plan.

The current staging system for rhabdomyosarcoma is unusual relative to most cancers. It utilizes a modified TNM (tumor-nodes-metastasis) system originally developed by the IRSG. This system accounts for tumor size (> or <5 cm), lymph node involvement, tumor site, and presence of metastasis. It grades on a scale of 1 to 4 based on these criteria. In addition, patients are sorted by clinical group (from the clinical groups from the IRSG studies) based on the success of their first surgical resection. The current Children's Oncology Group protocols for the treatment of RMS categorize patients into one of four risk categories based on tumor grade and clinical group, and these risk categories have been shown to be highly predictive of outcome.

Because of its rarity, there have been no randomized clinical trials of treatment of GCCL, and all information available derives from small retrospective institutional series or multicenter metadata.

Rhabdomyosarcoma is often difficult to diagnose due to its similarities to other cancers and varying levels of differentiation. It is loosely classified as one of the “small, round, blue-cell cancer of childhood” due to its appearance on an H&E stain. Other cancers that share this classification include neuroblastoma, Ewing sarcoma, and lymphoma, and a diagnosis of RMS requires confident elimination of these morphologically similar diseases. The defining diagnostic trait for RMS is confirmation of malignant skeletal muscle differentiation with myogenesis (presenting as a plump, pink cytoplasm) under light microscopy. Cross striations may or may not be present. Accurate diagnosis is usually accomplished through immunohistochemical staining for muscle-specific proteins such as myogenin, muscle-specific actin, desmin, D-myosin, and myoD1. Myogenin, in particular, has been shown to be highly specific to RMS, although the diagnostic significance of each protein marker may vary depending on the type and location of the malignant cells. The alveolar type of RMS tends to have stronger muscle-specific protein staining. Electron microscopy may also aid in diagnosis, with the presence of actin and myosin or Z bands pointing to a positive diagnosis of RMS. Classification into types and subtypes is accomplished through further analysis of cellular morphology (alveolar spacings, presence of cambium layer, aneuploidy, etc.) as well as genetic sequencing of tumor cells. Some genetic markers, such as the "PAX3-FKHR" fusion gene expression in alveolar RMS, can aid in diagnosis. Open biopsy is usually required to obtain sufficient tissue for accurate diagnosis. All findings must be considered in context, as no one trait is a definitive indicator for RMS.

Giant-cell lung cancers have long been considered to be exceptionally aggressive malignancies that grow very rapidly and have a very poor prognosis.

Many small series have suggested that the prognosis of lung tumors with giant cells is worse than that of most other forms of non-small-cell lung cancer (NSCLC), including squamous cell carcinoma, and spindle cell carcinoma.

The overall five-year survival rate in GCCL varies between studies but is generally considered to be very low. The (US) Armed Forces Institute of Pathology has reported a figure of 10%, and in a study examining over 150,000 lung cancer cases, a figure of 11.8% was given. However, in the latter report the 11.8% figure was based on data that included spindle cell carcinoma, a variant which is generally considered to have a less dismal prognosis than GCCL. Therefore, the likely survival of "pure" GCCL is probably lower than the stated figure.

In the large 1995 database review by Travis and colleagues, giant-cell carcinoma has the third-worst prognosis among 18 histological forms of lung cancer. (Only small-cell carcinoma and large-cell carcinoma had shorter average survival.)

Most GCCL have already grown and invaded locally and/or regionally, and/or have already metastasized distantly, and are inoperable, at the time of diagnosis.

In most series, LCLC's comprise between 5% and 10% of all lung cancers.

According to the Nurses' Health Study, the risk of large cell lung carcinoma increases with a previous history of tobacco smoking, with a previous smoking duration of 30 to 40 years giving a relative risk of approximately 2.3 compared to never-smokers, and a duration of more than 40 years giving a relative risk of approximately 3.6.

Another study concluded that cigarette smoking is the predominant cause of large cell lung cancer. It estimated that the odds ratio associated with smoking two or more packs/day for current smokers is 37.0 in men and 72.9 in women.

Ultrasound, CT scan, and MRI may be used to evaluate the liver for HCC. On CT and MRI, HCC can have three distinct patterns of growth:

- A single large tumor

- Multiple tumors

- Poorly defined tumor with an infiltrative growth pattern

A systematic review of CT diagnosis found that the sensitivity was 68 percent (95% CI 55-80%) and specificity was 93 percent (95% CI 89-96%) compared with pathologic examination of an explanted or resected liver as the reference standard. With triple-phase helical CT, the sensitivity 90% or higher, but this data has not been confirmed with autopsy studies.

However, MRI has the advantage of delivering high-resolution images of the liver without ionizing radiation. HCC appears as a high-intensity pattern on T2 weighted images and a low-intensity pattern on T1 weighted images. The advantage of MRI is that is has improved sensitivity and specificity when compared to US and CT in cirrhotic patients with whom it can be difficult to differentiate HCC from regenerative nodules. A systematic review found that the sensitivity was 81 percent (95% CI 70-91%) and specificity was 85 percent (95% CI 77-93%) compared with pathologic examination of an explanted or resected liver as the reference standard. The sensitivity is further increased if gadolinium contrast-enhanced and diffusion-weighted imaging are combined.

MRI is more sensitive and specific than CT.

Liver Image Reporting and Data System (LI-RADS) is a classification system for the reporting of liver lesions detected on CT and MRI. Radiologists use this standardized system to report on suspicious lesions and to provide an estimated likelihood of malignancy. Categories range from LI-RADS (LR) 1 to 5, in order of concern for cancer. A biopsy is not needed to confirm the diagnosis of HCC if certain imaging criteria are met.

The long-term use of supplemental vitamin A, vitamin C, vitamin D or vitamin E does not reduce the risk of lung cancer. Some studies suggest that people who eat diets with a higher proportion of vegetables and fruit tend to have a lower risk, but this may be due to confounding—with the lower risk actually due to the association of a high fruit/vegetables diet with less smoking. Several rigorous studies have not demonstrated a clear association between diet and lung cancer risk, although meta-analysis that accounts for smoking status may show benefit from a healthy diet.

LCC is, in effect, a "diagnosis of exclusion", in that the tumor cells lack light microscopic characteristics that would classify the neoplasm as a small-cell carcinoma, squamous-cell carcinoma, adenocarcinoma, or other more specific histologic type of lung cancer.

LCC is differentiated from small-cell lung carcinoma (SCLC) primarily by the larger size of the anaplastic cells, a higher cytoplasmic-to-nuclear size ratio, and a lack of "salt-and-pepper" chromatin.

After the initial diagnosis of Barrett's esophagus is rendered, affected persons undergo annual surveillance to detect changes that indicate higher risk to progression to cancer: development of epithelial dysplasia (or "intraepithelial neoplasia").

Considerable variability is seen in assessment for dysplasia among pathologists. Recently, gastroenterology and GI pathology societies have recommended that any diagnosis of high-grade dysplasia in Barrett be confirmed by at least two fellowship-trained GI pathologists prior to definitive treatment for patients. For more accuracy and reproductibility, it is also recommended to follow international classification system as the "Vienna classification" of gastrointestinal epithelial neoplasia (2000).

Staging of c-SCLC patients is usually performed in an analogous fashion to patients with "pure" small cell lung carcinoma.

For several decades, SCLC has been staged according to a dichotomous distinction of "limited disease" (LD) "vs." "extensive disease" (ED) tumor burdens. Nearly all clinical trials have been conducted on SCLC patients staged dichotomously in this fashion. LD is roughly defined as a locoregional tumor burden confined to one hemithorax that can be encompassed within a single, tolerable radiation field, and without detectable distant metastases beyond the chest or supraclavicular lymph nodes. A patient is assigned an ED stage when the tumor burden is greater than that defined under LD criteria — either far advanced locoregional disease, malignant effusions from the pleura or pericardium, or distant metastases.

However, more recent data reviewing outcomes in very large numbers of SCLC patients suggests that the TNM staging system used for NSCLC is also reliable and valid when applied to SCLC patients, and that more current versions may allow better treatment decisionmaking and prognostication in SCLC than with the old dichotomous staging protocol.