Historically, hematological malignancies have been most commonly divided by whether the malignancy is mainly located in the blood (leukemia) or in lymph nodes (lymphomas).

However, the influential WHO Classification (published in 2001) placed a greater emphasis on cell lineage.

Relative proportions of hematological malignancies in the United States

For the analysis of a suspected "hematological malignancy", a complete blood count and blood film are essential, as malignant cells can show in characteristic ways on light microscopy. When there is lymphadenopathy, a biopsy from a lymph node is generally undertaken surgically. In general, a bone marrow biopsy is part of the "work up" for the analysis of these diseases. All specimens are examined microscopically to determine the nature of the malignancy. A number of these diseases can now be classified by cytogenetics (AML, CML) or immunophenotyping (lymphoma, myeloma, CLL) of the malignant cells.

Some drugs are particularly effective against cancers which fit certain requirements. For example, Herceptin is very effective in patients who are Her2 positive, but much less effective in patients who are Her2 negative. Once the primary tumor is removed, biopsy of the current state of the cancer through traditional tissue typing is not possible anymore. Often tissue sections of the primary tumor, removed years prior, are used to do the typing. Further characterisation of CTC may help determining the current tumor phenotype. FISH assays has been performed on CTC to as well as determination of IGF-1R, Her2, Bcl-2, [ERG (gene)|ERG], PTEN, AR status using immunofluorescence. Single cell level qPCR can also be performed with the CTCs isolated from blood.

To date, a variety of research methods have been developed to isolate and enumerate CTC. The only U.S. Food and Drug Administration (FDA) cleared methodology for enumeration of CTC in whole blood is the CellSearch system. Extensive clinical testing done using this method shows that presence of CTC is a strong prognostic factor for overall survival in patients with metastatic breast, colorectal or prostate cancer, see figure 2

Leukemia is diagnosed in a variety of ways. Some diagnostic procedures include:

- A bone-marrow aspiration and biopsy; marrow may be removed by aspiration or a needle biopsy.

- A complete blood count, which is a measurement of size, number, and maturity of different blood cells in blood.

- Blood tests may include blood chemistry, evaluation of liver and kidney functions, and genetic studies.

- A lymph-node biopsy; lymph node tissue is surgically removed to examine under a microscope, to look for cancerous cells.

- A spinal tap: a special needle is placed into the lower back into the spinal canal, which is the area around the spinal cord. Cerebral spinal fluid is fluid that bathes the child's brain and spinal cord. A small amount of cerebral spinal fluid is sent for testing to determine if leukemia cells are present.

The symptoms of childhood rhabdomyosarcoma are visible and prominent and include swollen red lumps where the cancer starts developing. The lumps are hard and can grow in size unless treated. Other symptoms include poor bowel movements, blood in the urine, secretions from the genitals and nose, and headaches. Various tests can determine whether these related symptoms indicate childhood rhabdomyosarcoma. CT, X-ray, MRI, bone scans, and Ultrasounds may be performed to identify the location and size of the cancer. Biopsies of the lump can be taken along with bone marrow biopsies to detect whether the cancer has spread within the marrow, the bone, and the blood supply. Further determination of how aggressive and large the cancer is requires these scans.

The only reliable way to determine whether a soft-tissue tumour is benign or malignant is through a biopsy. There are two methods for acquisition of tumour tissue for cytopathological analysis;

- Needle Aspiration, via biopsy needle

- surgically, via an incision made into the tumour.

A pathologist examines the tissue under a microscope. If cancer is present, the pathologist can usually determine the type of cancer and its grade. Here, 'grade' refers to a scale used to represent concisely the predicted growth rate of the tumour and its tendency to spread, and this is determined by the degree to which the cancer cells appear abnormal when examined under a microscope. Low-grade sarcomas, although cancerous, are defined as those that are less likely to metastasise. High-grade sarcomas are defined as those more likely to spread to other parts of the body.

For soft-tissue sarcoma there are two histological grading systems : the National Cancer Institute (NCI) system and the French Federation of Cancer Centers Sarcoma Group (FNCLCC) system.

Soft tissue sarcomas commonly originate in the upper body, in the shoulder or upper chest. Some symptoms are uneven posture, pain in the trapezius muscle and cervical inflexibility [difficulty in turning the head].

The most common site to which soft tissue sarcoma spreads is the lungs.

The CBC provides a quantified measure of the different cells in the whole blood sample from the patient. Such cells examined for in this test include red blood cells (erythrocytes), white blood cells (leukocytes) and platelets (thrombocytes). A common sign of renal cell carcinoma is anaemia whereby the patient exhibits deficiency in red blood cells. CBC tests are vital as a screening tool for examination the health of patient prior to surgery. Inconsistencies with platelet counts are also common amongst these cancer patients and further coagulation tests, including Erythrocyte Sedimentation Rate (ESR), Prothrombin Time (PT), Activated Partial Thromboplastin Time (APTT) should be considered.

Magnetic Resonance Imaging (MRI) scans provide an image of the soft tissues in the body using radio waves and strong magnets. MRI can be used instead of CT if the patient exhibits an allergy to the contrast media administered for the test. Sometimes prior to the MRI scan, an intravenous injection of a contrasting material called gadolinium is given to allow for a more detailed image. Patients on dialysis or those who have renal insufficiency should avoid this contrasting material as it may induce a rare, yet severe, side effect known as nephrogenic systemic fibrosis. A bone scan or brain imaging is not routinely performed unless signs or symptoms suggest potential metastatic involvement of these areas.

MRI scans should also be considered to evaluate tumour extension which has grown in major blood vessels, including the vena cava, in the abdomen. MRI can be used to observe the possible spread of cancer to the brain or spinal cord should the patient present symptoms that suggest this might be the case.

Some tests which detect cancer could be called "screening for epithelial dysplasia". The principle behind these tests is that physicians expect dysplasia to occur at the same rate in a typical individual as it would in many other people. Because of this, researchers design screening recommendations which assume that if a physician can find no dysplasia at certain time, then doing testing before waiting until new dysplasia could potentially develop would be a waste of medical resources for the patient and the healthcare provider because the chances of detecting anything is extremely low.

Some examples of this in practice are that if a patient whose endoscopy did not detect dysplasia on biopsy during screening for Barrett's esophagus, then research shows that there is little chance of any test detecting dysplasia for that patient within three years.

Individuals at average-risk for colorectal cancer should have another screening after ten years if they get a normal result and after five years if they have only one or two adenomatous polyps removed.

Childhood rhabdomyosarcoma has been fatal. Recovery rates have increased by 50 percent since 1975. In children five years of age or younger survival rates are up to 65 percent. In adolescents younger than 15 years old, the survival rate has increased up to 30 percent.

Brain imaging (neuroimaging such as CT or MRI) is needed to determine the presence of brain metastases. In particular, contrast-enhanced MRI is the best method of diagnosing brain metastases, though detection is primarily done by CT. Biopsy is often recommended to confirm diagnosis.

The diagnosis of brain metastases typically follows a diagnosis of a systemic cancer. Occasionally, brain metastases will be diagnosed concurrently with a primary tumor or before the primary tumor is found.

Diagnosis is usually based on repeated complete blood counts and a bone marrow examination following observations of the symptoms. Sometimes, blood tests may not show that a person has leukemia, especially in the early stages of the disease or during remission. A lymph node biopsy can be performed to diagnose certain types of leukemia in certain situations.

Following diagnosis, blood chemistry tests can be used to determine the degree of liver and kidney damage or the effects of chemotherapy on the patient. When concerns arise about other damage due to leukemia, doctors may use an X-ray, MRI, or ultrasound. These can potentially show leukemia's effects on such body parts as bones (X-ray), the brain (MRI), or the kidneys, spleen, and liver (ultrasound). CT scans can be used to check lymph nodes in the chest, though this is uncommon.

Despite the use of these methods to diagnose whether or not a patient has leukemia, many people have not been diagnosed because many of the symptoms are vague, non-specific, and can refer to other diseases. For this reason, the American Cancer Society estimates that at least one-fifth of the people with leukemia have not yet been diagnosed.

The first test for diagnosis myelophthisis involves looking at a small sample of blood under a microscope. Myelophthisis is suggested by the presence of red blood cells that contain nuclei or are teardrop-shaped (dacryocytes), or immature granulocyte precursor cells which indicates leukoerythroblastosis is occurring because the displaced hematopoietic cells begin to undergo extramedullary hematopoiesis. These immature granulocytes are seen in peripheral blood smears. Diagnosis is confirmed when a bone marrow biopsy demonstrates significant replacement of the normal bone marrow compartment by fibrosis, malignancy or other infiltrative process. The presence of immature blood cell precursors helps distinguish another cause of pancytopenia, aplastic anemia, from myelophthisic anemia because in aplastic anemia the hematopoietic cells are damaged and immature blood cells are not seen in the peripheral blood.

There may be evidence of extramedullary hematopoiesis (marrow elements can be found in the spleen, liver).

As soon as a tumor is detected, diagnosing the type of cancer remains a primary objective, as it helps determine the best possible treatment by the analysis of the structure of the tumor and cancer cells.

In general, treatment for soft-tissue sarcomas depends on the stage of the cancer. The stage of the sarcoma is based on the size and grade of the tumor, and whether the cancer has spread to the lymph nodes or other parts of the body (metastasized). Treatment options for soft-tissue sarcomas include surgery, radiation therapy, and chemotherapy.

- Surgery is the most common treatment for soft-tissue sarcomas. If possible, the doctor will remove the cancer and a safe margin of the healthy tissue around it. It is important to obtain a margin free of tumor to decrease the likelihood of local recurrence and give the best chance for eradication of the tumor. Depending on the size and location of the sarcoma, it may, rarely, be necessary to remove all or part of an arm or leg.

- Radiation therapy may be used either before surgery to shrink tumors or after surgery to kill any cancer cells that may have been left behind. In some cases, it can be used to treat tumours that cannot be surgically removed. In multiple studies, radiation therapy has been found to improve the rate of local control, but has not had any influence on overall survival.

- Chemotherapy may be used with radiation therapy either before or after surgery to try to shrink the tumor or kill any remaining cancer cells. The use of chemotherapy to prevent the spread of soft-tissue sarcomas has not been proven to be effective. If the cancer has spread to other areas of the body, chemotherapy may be used to shrink tumors and reduce the pain and discomfort they cause, but is unlikely to eradicate the disease.

Treatment options vary and depend on the type and stage of cancer. Common treatments include surgery, chemotherapy, radiation therapy, amputation, and immunotherapy. A combination of therapies may be used. Knowledge and treatment of cancer have increased significantly in the past three decades. Survival rates have also increased due to the increase prevalence of canine cancer treatment centers and breakthroughs in targeted drug development. Canine cancer treatment has become an accepted clinical practice and access to treatment for owners has widely expanded recently. Cancer-targeting drugs most commonly function to inhibit excessive cell proliferation by attacking the replicating cells. However, there is still a prevalent pharmacy gap in veterinary oncology.

There is one canine tumor vaccine approved by the USDA, for preventing canine melanoma. The Oncept vaccine activates T-cell responses and antibodies against tumor-specific tyrosinase proteins. There is limited information about canine tumor antigens, which is the reason for the lack of tumor-specific vaccines and immunotherapy treatment plans for dogs.

Success of treatment depends on the form and extent of the cancer and the aggressiveness of the therapy. Early detection offers the best chance for successful treatment. The heterogeneity of tumors makes drug development increasingly complex, especially as new causes are discovered. No cure for cancer in canines exist.

Some dog owners opt for no treatment of the cancer at all, in which case palliative care, including pain relief, may be offered. Regardless of how treatment proceeds following a diagnosis, the quality of life of the pet is an important consideration. In cases where the cancer is not curable, there are still many things which can be done to alleviate the dog's pain. Good nutrition and care from the dog's owner can greatly enhance quality of life.

The treatment a child will undergo is based on the child's age, overall health, medical history, their tolerance for certain medications, procedures, and therapies, along with the parents' opinion and preference.

- Chemotherapy is a treatment that uses drugs to interfere with the cancer cells ability to grow and reproduce. Chemotherapy can be used alone or in combination with other therapies. Chemotherapy can be given either as a pill to swallow orally, an injection into the fat or muscle, through an IV directly into the bloodstream, or directly into the spinal column.

- A stem cell transplant is a process by which healthy cells are infused into the body. A stem-cell transplant can help the human body make enough healthy white blood cells, red blood cells, or platelets, and reduce the risk of life-threatening infections, anemia, and bleeding. It is also known as a bone-marrow transplant or an umbilical-cord blood transplant, depending on the source of the stem cells. Stem cell transplants can use the cells from the same person, called an autologous stem cell transplant or they can use stem cells from other people, known as an allogenic stem cell transplant. In some cases, the parents of a child with childhood leukemia may conceive a saviour sibling by preimplantation genetic diagnosis to be an appropriate match for the HLA antigen.

Treatments of cancer in cats usually consists of diagnosis and observation of the tumor to determine its type and size, the development of a treatment plan, the associated goals on the part of the treatment methods, and the regular evaluation of the overall health of the pet.

Treatment and survival is determined, to a great extent, by whether or not a cancer remains localized or spreads to other locations in the body. If the cancer metastasizes to other tissues or organs it usually dramatically increases a patient's likelihood of death. Some cancers—such as some forms of leukemia, a cancer of the blood, or malignancies in the brain—can kill without spreading at all.

Once a cancer has metastasized it may still be treated with radiosurgery, chemotherapy, radiation therapy, biological therapy, hormone therapy, surgery, or a combination of these interventions ("multimodal therapy"). The choice of treatment depends on a large number of factors, including the type of primary cancer, the size and location of the metastases, the patient's age and general health, and the types of treatments used previously. In patients diagnosed with CUP it is often still possible to treat the disease even when the primary tumor cannot be located.

Current treatments are rarely able to cure metastatic cancer though some tumors, such as testicular cancer and thyroid cancer, are usually curable.

Palliative care, care aimed at improving the quality of life of people with major illness, has been recommended as part of management programs for metastasis.

Leukemia is rarely associated with pregnancy, affecting only about 1 in 10,000 pregnant women. How it is handled depends primarily on the type of leukemia. Nearly all leukemias appearing in pregnant women are acute leukemias. Acute leukemias normally require prompt, aggressive treatment, despite significant risks of pregnancy loss and birth defects, especially if chemotherapy is given during the developmentally sensitive first trimester. Chronic myelogenous leukemia can be treated with relative safety at any time during pregnancy with Interferon-alpha hormones. Treatment for chronic lymphocytic leukemias, which are rare in pregnant women, can often be postponed until after the end of the pregnancy.

The first red flag that indicates M2 acute myeloblastic leukemia with maturation is the skewed ratio of white blood cells to red blood cells. Leukemia is initially diagnosed by a peripheral blood smear, a procedure used to check for cell count and cell shapes. Then a bone marrow aspiration and biopsy would be conducted to collect and view the bone, bone marrow, and blood under a microscope. Cytogenetic assays, such as fluorescence in situ hybridization (FISH) would help evaluate the structure and function of the cell’s chromosomes.

The criteria for an acute myeloid leukemia case to fall under the M2 subtype is the following: 20%+ nonerythroid cells in peripheral blood or bone marrow are myeloblasts; monocytic precursors are < 20% in bone marrow and granulocytes are 10%+ of cells (Mihova, 2013).

The U.S. Preventive Services Task Force (USPSTF) issues recommendations for various cancers:

- Strongly recommends cervical cancer screening in women who are sexually active and have a cervix at least until the age of 65.

- Recommend that Americans be screened for colorectal cancer via fecal occult blood testing, sigmoidoscopy, or colonoscopy starting at age 50 until age 75.

- Evidence is insufficient to recommend for or against screening for skin cancer, oral cancer, lung cancer, or prostate cancer in men under 75.

- Routine screening is not recommended for bladder cancer, testicular cancer, ovarian cancer, pancreatic cancer, or prostate cancer.

- Recommends mammography for breast cancer screening every two years from ages 50–74, but does not recommend either breast self-examination or clinical breast examination. A 2013 Cochrane review concluded that breast cancer screening by mammography had no effect in reducing mortality because of overdiagnosis and overtreatment.

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.

Screens for gastric cancer using photofluorography due to the high incidence there.