Stomach cancer is often either asymptomatic (producing no noticeable symptoms) or it may cause only nonspecific symptoms (symptoms that may also be present in other related or unrelated disorders) in its early stages. By the time symptoms occur, the cancer has often reached an advanced stage (see below) and may have metastasized (spread to other, perhaps distant, parts of the body), which is one of the main reasons for its relatively poor prognosis. Stomach cancer can cause the following signs and symptoms:

Early cancers may be associated with indigestion or a burning sensation (heartburn). However, less than 1 in every 50 people referred for endoscopy due to indigestion has cancer. Abdominal discomfort and loss of appetite, especially for meat, can occur.

Gastric cancers that have enlarged and invaded normal tissue can cause weakness, fatigue, bloating of the stomach after meals, abdominal pain in the upper abdomen, nausea and occasional vomiting, diarrhea or constipation. Further enlargement may cause weight loss or bleeding with vomiting blood or having blood in the stool, the latter apparent as black discolouration (melena) and sometimes leading to anemia. Dysphagia suggests a tumour in the cardia or extension of the gastric tumour into the esophagus.

These can be symptoms of other problems such as a stomach virus, gastric ulcer, or tropical sprue.

Symptoms of anal cancer can include pain or pressure in the anus or rectum, a change in bowel habits, a lump near the anus, rectal bleeding, itching or discharge. Bleeding may be severe.

Prominent symptoms usually do not appear until the cancer has infiltrated over 60% of the circumference of the esophageal tube, by which time the tumor is already in an advanced stage. Onset of symptoms is usually caused by narrowing of the tube due to the physical presence of the tumor.

The first and the most common symptom is usually difficulty in swallowing, which is often experienced first with solid foods and later with softer foods and liquids. Pain when swallowing is less usual at first. Weight loss is often an initial symptom in cases of squamous-cell carcinoma, though not usually in cases of adenocarcinoma. Eventual weight loss due to reduced appetite and undernutrition is common. Pain behind the breastbone or in the region around the stomach often feels like heartburn. The pain can frequently be severe, worsening when food of any sort is swallowed. Another sign may be an unusually husky, raspy, or hoarse-sounding cough, a result of the tumor affecting the recurrent laryngeal nerve.

The presence of the tumor may disrupt the normal contractions of the esophagus when swallowing. This can lead to nausea and vomiting, regurgitation of food and coughing. There is also an increased risk of aspiration pneumonia due to food entering the airways through the abnormal connections (fistulas) that may develop between the esophagus and the trachea (windpipe). Early signs of this serious complication may be coughing on drinking or eating. The tumor surface may be fragile and bleed, causing vomiting of blood. Compression of local structures occurs in advanced disease, leading to such problems as upper airway obstruction and superior vena cava syndrome. Hypercalcemia (excess calcium in the blood) may occur.

If the cancer has spread elsewhere, symptoms related to metastatic disease may appear. Common sites of spread include nearby lymph nodes, the liver, lungs and bone. Liver metastasis can cause jaundice and abdominal swelling (ascites). Lung metastasis can cause, among other symptoms, impaired breathing due to excess fluid around the lungs (pleural effusion), and dyspnea (the feelings often associated with impaired breathing).

Anal cancer is a cancer (malignant tumor) which arises from the anus, the distal opening of the gastrointestinal tract. It is a distinct entity from the more common colorectal cancer.

Anal cancer is typically an anal squamous cell carcinoma that arises near the squamocolumnar junction, often linked to human papillomavirus (HPV) infection. It may be keratinizing (basaloid) or non-keratinizing (cloacogenic). Other types of anal cancer are adenocarcinoma, lymphoma, sarcoma or melanoma. From data collected 2004-2010, the relative five year survival rate in the United States is 65.5%, though individual rates may vary depending upon the stage of cancer at diagnosis and the response to treatment.

Stomach cancer, also known as gastric cancer, is cancer developing from the lining of the stomach. Early symptoms may include heartburn, upper abdominal pain, nausea and loss of appetite. Later signs and symptoms may include weight loss, yellowing of the skin and whites of the eyes, vomiting, difficulty swallowing, and blood in the stool among others. The cancer may spread from the stomach to other parts of the body, particularly the liver, lungs, bones, lining of the abdomen and lymph nodes.

The most common cause is infection by the bacterium "Helicobacter pylori", which accounts for more than 60% of cases. Certain types of "H. pylori" have greater risks than others. Smoking, dietary factors such as pickled vegetables, and obesity are other risk factors. About 10% of cases run in families and between 1% and 3% of cases are due to genetic syndromes inherited from a person's parents such as hereditary diffuse gastric cancer. Most cases of stomach cancers are gastric carcinomas. This type can be divided into a number of subtypes. Lymphomas and mesenchymal tumors may also develop in the stomach. Most of the time, stomach cancer develops in stages over years. Diagnosis is usually by biopsy done during endoscopy. This is followed by medical imaging to determine if the disease has spread to other parts of the body. Japan and South Korea, two countries that have high rates of the disease, screen for stomach cancer.

A Mediterranean diet lowers the risk of cancer as does the stopping of smoking. There is tentative evidence that treating "H. pylori" decreases the future risk. If cancer is treated early, many cases can be cured. Treatments may include some combination of surgery, chemotherapy, radiation therapy, and targeted therapy. If treated late, palliative care may be advised. Outcomes are often poor with a less than 10% five-year survival rate globally. This is largely because most people with the condition present with advanced disease. In the United States five-year survival is 28% while in South Korea it is over 65% partly due to screening efforts.

Globally, stomach cancer is the fifth leading cause of cancer and the third leading cause of death from cancer making up 7% of cases and 9% of deaths. In 2012, it newly occurred in 950,000 people and caused 723,000 deaths. Before the 1930s, in much of the world, including most Western developed countries, it was the most common cause of death from cancer. Rates of death have been decreasing in many areas of the world since then. This is believed to be due to the eating of less salted and pickled foods as a result of the development of refrigeration as a method of keeping food fresh. Stomach cancer occurs most commonly in East Asia and Eastern Europe. It occurs twice as often in males as in females.

Gastrointestinal cancer refers to malignant conditions of the gastrointestinal tract (GI tract) and accessory organs of digestion, including the esophagus, stomach, biliary system, pancreas, small intestine, large intestine, rectum and anus. The symptoms relate to the organ affected and can include obstruction (leading to difficulty swallowing or defecating), abnormal bleeding or other associated problems. The diagnosis often requires endoscopy, followed by biopsy of suspicious tissue. The treatment depends on the location of the tumor, as well as the type of cancer cell and whether it has invaded other tissues or spread elsewhere. These factors also determine the prognosis.

Overall, the GI tract and the accessory organs of digestion (pancreas, liver, gall bladder) are responsible for more cancers and more deaths from cancer than any other system in the body. There is significant geographic variation in the rates of different gastrointestinal cancers.

Pancreatic cancer is the fifth-most-common cause of cancer deaths in the United States, and the seventh most common in Europe. In 2008, globally there were 280,000 new cases of pancreatic cancer reported and 265,000 deaths. These cancers are classified as endocrine or nonendocrine tumors. The most common is ductal adenocarcinoma. The most significant risk factors for pancreatic cancer are advanced age (over 60) and smoking. Chronic pancreatitis, diabetes or other conditions may also be involved in their development. Early pancreatic cancer does not tend to result in any symptom, but when a tumor is advanced, a patient may experience severe pain in the upper abdomen, possibly radiating to the back. Another symptom might be jaundice, a yellowing of the skin and eyes.

Pancreatic cancer has a poor prognosis, with a five-year survival rate of less than 5%. By the time the cancer is diagnosed, it is usually at an advanced, inoperable stage. Only one in about fifteen to twenty patients is curative surgery attempted. Pancreatic cancer tends to be aggressive, and it resists radiotherapy and chemotherapy.

Adenocarcinoma (; plural adenocarcinomas or adenocarcinomata ) is a type of cancerous tumor that can occur in several parts of the body. It is defined as neoplasia of epithelial tissue that has glandular origin, glandular characteristics, or both. Adenocarcinomas are part of the larger grouping of carcinomas, but are also sometimes called by more precise terms omitting the word, where these exist. Thus invasive ductal carcinoma, the most common form of breast cancer, is adenocarcinoma but does not use the term in its name—however, esophageal adenocarcinoma does to distinguish it from the other common type of esophageal cancer, esophageal squamous cell carcinoma. Several of the most common forms of cancer are adenocarcinomas, and the various sorts of adenocarcinoma vary greatly in all their aspects, so that few useful generalizations can be made about them.

In the most specific usage (narrowest sense), the glandular origin or traits are exocrine; endocrine gland tumors, such as a VIPoma, an insulinoma, or a pheochromocytoma, are typically not referred to as adenocarcinomas but rather are often called neuroendocrine tumors. Epithelial tissue sometimes includes, but is not limited to, the surface layer of skin, glands, and a variety of other tissue that lines the cavities and organs of the body. Epithelial tissue can be derived embryologically from any of the germ layers (ectoderm, endoderm, or mesoderm). To be classified as adenocarcinoma, the cells do not necessarily need to be part of a gland, as long as they have secretory properties. Adenocarcinoma is the malignant counterpart to adenoma, which is the benign form of such tumors. Sometimes adenomas transform into adenocarcinomas, but most do not.

Well differentiated adenocarcinomas tend to resemble the glandular tissue that they are derived from, while poorly differentiated adenocarcinomas may not. By staining the cells from a biopsy, a pathologist can determine whether the tumor is an adenocarcinoma or some other type of cancer. Adenocarcinomas can arise in many tissues of the body owing to the ubiquitous nature of glands within the body, and, more fundamentally, to the potency of epithelial cells. While each gland may not be secreting the same substance, as long as there is an exocrine function to the cell, it is considered glandular and its malignant form is therefore named adenocarcinoma.

Signs and symptoms of TCC are entirely dependent on the location and extent of the cancer.

Esophageal cancer may be due to either squamous cell carcinoma (ESCC) or adenocarcinoma (EAC). SCCs tend to occur closer to the mouth, while adenocarcinomas occur closer to the stomach. Dysphagia (difficulty swallowing, solids worse than liquids) and painful swallowing are common initial symptoms. If the disease is localized, surgical removal of the affected esophagus may offer the possibility of a cure. If the disease has spread, chemotherapy and radiotherapy are commonly used.

Esophageal cancer is cancer arising from the esophagus—the food pipe that runs between the throat and the stomach. Symptoms often include difficulty in swallowing and weight loss. Other symptoms may include pain when swallowing, a hoarse voice, enlarged lymph nodes ("glands") around the collarbone, a dry cough, and possibly coughing up or vomiting blood.

The two main sub-types of the disease are esophageal squamous-cell carcinoma (often abbreviated to ESCC), which is more common in the developing world, and esophageal adenocarcinoma (EAC), which is more common in the developed world. A number of less common types also occur. Squamous-cell carcinoma arises from the epithelial cells that line the esophagus. Adenocarcinoma arises from glandular cells present in the lower third of the esophagus, often where they have already transformed to intestinal cell type (a condition known as Barrett's esophagus). Causes of the squamous-cell type include tobacco, alcohol, very hot drinks, poor diet, and chewing betel nut. The most common causes of the adenocarcinoma type are smoking tobacco, obesity, and acid reflux.

The disease is diagnosed by biopsy done by an endoscope (a fiberoptic camera). Prevention includes stopping smoking and eating a healthy diet. Treatment is based on the cancer's stage and location, together with the person's general condition and individual preferences. Small localized squamous-cell cancers may be treated with surgery alone with the hope of a cure. In most other cases, chemotherapy with or without radiation therapy is used along with surgery. Larger tumors may have their growth slowed with chemotherapy and radiation therapy. In the presence of extensive disease or if the affected person is not fit enough to undergo surgery, palliative care is often recommended.

As of 2012, esophageal cancer was the eighth-most common cancer globally with 456,000 new cases during the year. It caused about 400,000 deaths that year, up from 345,000 in 1990. Rates vary widely among countries, with about half of all cases occurring in China. It is around three times more common in men than in women. Outcomes are related to the extent of the disease and other medical conditions, but generally tend to be fairly poor, as diagnosis is often late. Five-year survival rates are around 13% to 18%.

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.

Signet ring cell carcinoma (SRCC) is a rare form of highly malignant adenocarcinoma that produces mucin. It is an epithelial malignancy characterized by the histologic appearance of signet ring cells.

Primary SRCC tumors are most often found in the glandular cells of the stomach (SRCC originates in the stomach in 90 percent of patients), and less frequently in the breast, gallbladder, urinary bladder, and pancreas. SRCCs do not normally form in the lungs, though a few incidences have been reported.

Among colorectal cancers, the prevalence of SRCC is less than one percent. Though incidence and mortality of gastric cancer has declined in many countries over the past 50 years, there has been an increase in occurrences of gastric SRCC-type cancers.

SRCC tumors grow in characteristic sheets, which makes diagnosis using standard imaging techniques, like CT and PET scans, less effective.

Metaplastic carcinoma is cancer that begins in cells that have changed into another cell type (for example, a squamous cell of the esophagus changing to resemble a cell of the stomach). In some cases, metaplastic changes alone may mean there is an increased chance of cancer developing at the site. Metaplastic carcinoma is a relatively uncommon type of cancer with treatment generally similar to that of invasive ductal carcinoma of no special type.

Transitional cell carcinoma (TCC) also urothelial carcinoma (UCC), is a type of cancer that typically occurs in the urinary system. It is the most common type of bladder cancer and cancer of the ureter, urethra, and urachus. It is the second most common type of kidney cancer, but accounts for only five to 10 percent of all primary renal malignant tumors.

TCC arises from the transitional epithelium, a tissue lining the inner surface of these hollow organs.

When the term "urothelial" is used, it specifically refers to a carcinoma of the urothelium, meaning a TCC of the urinary system.

Diffuse stomach cancer is characterized by the presence of poorly differentiated tumor cells. Microscopic appearance is signet ring cell carcinoma, which is tumor cells with mucin droplet that displaces the nucleus to one side.

The appearance of the stomach is like a "leather bottle". It is characterized by a thick, rigid stomach wall caused by diffuse infiltration of tumor cells and extensive fibrosis.

Diarrhea may be a presenting symptom.

Medullary carcinoma may refer to one of several different tumors of epithelial origin. As the term "" is a generic anatomic descriptor for the mid-layer of various organ tissues, a medullary tumor usually arises from the "mid-layer tissues" of the relevant organ.

Medullary carcinoma most commonly refers to:

- Medullary thyroid cancer

- Medullary carcinoma of the breast

Medullary carcinoma may also refer to tumors of:

- Pancreas

- Ampulla of Vater

- Gallbladder

- Stomach

- Large intestine

- Kidney — Renal medullary carcinoma

Examples of cancers where adenocarcinomas are a common form:

- esophageal cancer; most cases in the developed world are adenocarcinomas.

- pancreas; over 80% of pancreatic cancers are ductal adenocarcinomas.

- prostate cancer is nearly always adenocarcinoma

- cervical cancer: most is squamous cell cancer, but 10–15% of cervical cancers are adenocarcinomas

- stomach cancer

In many cases, ductal carcinoma is asymptomatic, and detected as abnormal results on mammography. When symptoms occur, a painless, enlarging mass that does not fluctuate with the menstrual period may be felt. Pinching of the overlying skin may also be seen. Certain subtypes, such as inflammatory carcinomas, may result in a swollen, enlarged and tender breast. All variants of cancer, if there is metastatic spread, may cause enlarged lymph nodes and affect other organs.

Invasive carcinoma of no special type (NST) is the most common form of invasive breast cancer. It accounts for 55% of breast cancer incidence upon diagnosis, according to statistics from the United States in 2004. On a mammogram, it is usually visualized as a mass with fine spikes radiating from the edges. On physical examination, this lump usually feels much harder or firmer than benign breast lesions such as fibroadenoma. On microscopic examination, the cancerous cells invade and replace the surrounding normal tissues. IDC is divided in several histological subtypes.

The early lesions are usually asymptomatic. The patients presenting with an advanced stage of the disease comprises around 66-77% of the cases.

The most important signs include a lump in the neck when palpated and weight loss.

People may also present with fatigue as a symptom.

The primary tumor does not have readily discernible signs or symptoms as they grow within the tonsillar capsule. It is difficult to notice anything suspicious on examination of the tonsil other than slight enlargement or the development of firmness around the area.

The carcinoma may occur in one or more sites deep within the tonsillar crypts. It may be accompanied by the enlargement of the tonsil. The affected tonsil grows into the oropharyngeal space making it noticeable by the patient in the form of a neck mass mostly in the jugulodiagastric region.

As the tonsils consist of a rich network of lymphatics, the carcinoma may metastasise to the neck lymph nodes which many are cystic.

Extension of tumor to skull or mediastinum can occur.

The additional symptoms include a painful throat, dysphagia, otalgia (due to cranial nerve involvement), foreign body sensation, bleeding, fixation of tongue (infiltration of deep muscles) and trismus (if the pterygoid muscle is involved in the parapharyngeal space).

On the other hand, the tumor may also present as a deep red or white fungating wound growing outwards, breaking the skin surface with a central ulceration. This wound-like ulcer fails to heal (non-healing) leading to bleeding and throat pain and other associated symptoms.

During biopsy, the lesion may show three signs: Gritty texture, Firmness and cystification owing to keratinization, fribrosis and necrosis respectively.

Cervical lymphydenopathy may be present.

Hepatoid tumor or hepatoid [adeno]carcinoma are terms for a number of uncommon or rare neoplasms in humans, named for a visual resemblance of the cells under the microscope to those of hepatocellular carcinoma, the most common form of liver cancer. They can arise in several parts of the body, and thus form sub-types of diseases such as stomach cancer and pancreatic cancer. The WHO defines "Hepatoid carcinoma" as "An adenocarcinoma with morphologic characteristics similar to hepatocellular carcinoma , arising from an anatomic site other than the liver".

In dogs it may refer to a Perianal gland tumor, based on a similar resemblance to healthy liver cells.

Penile cancer arises from precursor lesions, which generally progress from low-grade to high-grade lesions. For HPV related penile cancers this sequence is as follows:

- A. Squamous hyperplasia;

- B. Low-grade penile intraepithelial neoplasia (PIN);

- C. High-grade PIN (carcinoma in situ—Bowen's disease, Erythroplasia of Queyrat and bowenoid papulosis (BP));

- D. Invasive Carcinoma of the Penis.

However, in some cases non-dysplastic or mildly dysplastic lesions may progress directly into cancer. Examples include flat penile lesions (FPL) and condylomata acuminata.

In HPV negative cancers the most common precursor lesion is lichen sclerosus (LS).

Like many malignancies, penile cancer can spread to other parts of the body. It is usually a primary malignancy, the initial place from which a cancer spreads in the body. Much less often it is a secondary malignancy, one in which the cancer has spread to the penis from elsewhere. The staging of penile cancer is determined by the extent of tumor invasion, nodal metastasis, and distant metastasis.

The T portion of the AJCC TNM staging guidelines are for the primary tumor as follows:

- TX: Primary tumor cannot be assessed.

- T0: No evidence of primary tumor.

- Tis: Carcinoma "in situ".

- Ta: Noninvasive verrucous carcinoma.

- T1a: Tumor invades subepithelial connective tissue without lymph vascular invasion and is not poorly differentiated (i.e., grade 3–4).

- T1b: Tumor invades subepithelial connective tissue with lymph vascular invasion or is poorly differentiated.

- T2: Tumor invades the corpus spongiosum or cavernosum.

- T3: Tumor invades the urethra or prostate.

- T4: Tumor invades other adjacent structures.

Anatomic Stage or Prognostic Groups of penile cancer are as follows:

- Stage 0—Carcinoma "in situ".

- Stage I—The cancer is moderately or well differentiated and only affects the subepithelial connective tissue.

- Stage II—The cancer is poorly differentiated, affects lymphatics, or invades the corpora or urethra.

- Stage IIIa—There is deep invasion into the penis and metastasis in one lymph node.

- Stage IIIb—There is deep invasion into the penis and metastasis into multiple inguinal lymph nodes.

- Stage IV—The cancer has invaded into structures adjacent to the penis, metastasized to pelvic nodes, or distant metastasis is present.

Signs and symptoms of pseudomyxoma peritonei may include abdominal or pelvic pain and/or bloating, distension, digestive disorders, weight changes, increased girth, and infertility.