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When Polycythemia Vera Turns Into Another Cancer

SOURCES:

American Cancer Society: "What are Myelodysplastic Syndromes?"

Blood Cancer Journal: "Blast Transformation and Fibrotic Progression in Polycythemia Vera and Essential Thrombocythemia: A Literature Review of Incidence and Risk Factors,"  "Polycythemia Vera Treatment Algorithm 2018."

Canadian Cancer Society: "Polycythemia Vera."

Leukemia & Lymphoma Society: "Myelofibrosis Facts," "Polycythemia Vera Facts."

Mayo Clinic: "Acute Myelogenous Leukemia," "Polycythemia Vera," "Myelodysplastic Syndromes."

MedPage Today: "Polycythemia Vera to Blast Phase: New Findings."

Medscape: "Polycythemia Vera Follow-Up."

MPN Research Foundation: "What is Primary Myelofibrosis?" "Understanding the Symptoms of MPNS."

National Cancer Institute: "Adult Acute Myeloid Leukemia Treatment."

National Heart, Lung, and Blood Institute: "Polycythemia Vera."

National Organization for Rare Disorders: "Polycythemia Vera."

The Myelodysplastic Syndromes Foundation: "Frequently Asked Questions About MDS."

Voices of MPN: "When Polycythemia Vera Becomes Myelofibrosis."

Cancer Classification

Cancers may be classified by their primary site of origin or by their histological or tissue types.

Classification by site of origin

By primary site of origin, cancers may be of specific types like breast cancer, lung cancer, prostate cancer, liver cancer renal cell carcinoma (kidney cancer), oral cancer, brain cancer etc.

Classification by tissue types

The international standard for the classification and nomenclature of histologies is the International Classification of Diseases for Oncology, Third Edition (ICD-O-3). This classification is based on the ICD-O-3.

Based on tissue types cancers may be classified into six major categories:

1. Carcinoma

This type of cancer originates from the epithelial layer of cells that form the lining of external parts of the body or the internal linings of organs within the body.

Carcinomas, malignancies of epithelial tissue, account for 80 to 90 percent of all cancer cases since epithelial tissues are most abundantly found in the body from being present in the skin to the covering and lining of organs and internal passageways, such as the gastrointestinal tract.

Carcinomas usually affect organs or glands capable of secretion including breast, lungs, bladder, colon and prostate.

Carcinomas are of two types – adenocarcinoma and squamous cell carcinoma. Adenocarcinoma develops in an organ or gland and squamous cell carcinoma originates in squamous epithelium. Adenocarcinomas may affect mucus membranes and are first seen as a thickened plaque-like white mucosa. These are rapidly spreading cancers.

2. Sarcoma

These cancers originate in connective and supportive tissues including muscles, bones, cartilage and fat. Bone cancer is one of the sarcomas termed osteosarcoma. It affects the young most commonly. Sarcomas appear like the tissue in which they grow.

Other examples include chondrosarcoma (of the cartilage), leiomyosarcoma (smooth muscles), rhabdomyosarcoma (skeletal muscles), Mesothelial sarcoma or mesothelioma (membranous lining of body cavities), Fibrosarcoma (fibrous tissue), Angiosarcoma or hemangioendothelioma (blood vessels), Liposarcoma (adipose or fatty tissue), Glioma or astrocytoma (neurogenic connective tissue found in the brain), Myxosarcoma (primitive embryonic connective tissue) and Mesenchymous or mixed mesodermal tumor (mixed connective tissue types).

3. Myeloma

These originate in the plasma cells of bone marrow. Plasma cells are capable of producing various antibodies in response to infections. Myeloma is a type of blood cancer.

4. Leukemia

This a group of cancers that are grouped within blood cancers. These cancers affect the bone marrow which is the site for blood cell production. When cancerous, the bone marrow begins to produce excessive immature white blood cells that fail to perform their usual actions and the patient is often prone to infection.

Types of leukemia include:

Acute myelocytic leukemia (AML) – these are malignancy of the myeloid and granulocytic white blood cell series seen in childhood.

Chronic myelocytic leukemia (CML) – this is seen in adulthood.

Acute Lymphatic, lymphocytic, or lymphoblastic leukemia (ALL) – these are malignancy of the lymphoid and lymphocytic blood cell series seen in childhood and young adults.

Chronic Lymphatic, lymphocytic, or lymphoblastic leukemia (CLL) – this is seen in the elderly.

Polycythemia vera or erythremia – this is cancer of various blood cell products with a predominance of red blood cells.

5. Lymphoma

These are cancers of the lymphatic system. Unlike the leukemias, which affect the blood and are called "liquid cancers", lymphomas are "solid cancers". These may affect lymph nodes at specific sites like stomach, brain, intestines etc. These lymphomas are referred to as extranodal lymphomas.

Lymphomas may be of two types – Hodgkin's lymphoma and Non-Hodgkin's lymphomas. In Hodgkin lymphoma there is characteristic presence of Reed-Sternberg cells in the tissue samples which are not present in Non-Hodgkin lymphoma.

6. Mixed types

These have two or more components of the cancer. Some of the examples include mixed mesodermal tumor, carcinosarcoma, adenosquamous carcinoma and teratocarcinoma. Blastomas are another type that involves embryonic tissues.

Classification by grade

Cancers can also be classified according to grade. The abnormality of the cells with respect to surrounding normal tissues determines the grade of the cancer. Increasing abnormality increases the grade, from 1–4.

Cells that are well differentiated closely resemble normal specialized cells and belong to low grade tumors. Cells that are undifferentiated are highly abnormal with respect to surrounding tissues. These are high grade tumors.

Grade 1 – well differentiated cells with slight abnormality

Grade 2 – cells are moderately differentiated and slightly more abnormal

Grade 3 – cells are poorly differentiated and very abnormal

Grade 4 – cells are immature and primitive and undifferentiated

Classification by stage

Cancers are also classified individually according to their stage. There are several types of staging methods. The most commonly used method uses classification in terms of tumor size (T), the degree of regional spread or node involvement (N), and distant metastasis (M). This is called the TNM staging.

For example, T0 signifies no evidence of tumor, T 1 to 4 signifies increasing tumor size and involvement and Tis signifies carcinoma in situ or limited to surface cells. Similarly N0 signifies no nodal involvement and N 1 to 4 signifies increasing degrees of lymph node involvement. Nx signifies that node involvement cannot be assessed. Metastasis is further classified into two – M0 signifies no evidence of distant spread while M1 signifies evidence of distant spread.

Stages may be divided according to the TNM staging classification. Stage 0 indicates cancer being in situ or limited to surface cells while stage I indicates cancer being limited to the tissue of origin. Stage II indicates limited local spread, Stage II indicates extensive local and regional spread while stage IV is advanced cancer with distant spread and metastasis.

Sources

http://training.Seer.Cancer.Gov/disease/categories/classification.Html

https://www.Weizmann.Ac.Il/pages/

https://www.Societederecherchesurlecancer.Ca/fr

Further Reading

11 Symptoms Of Blood Cancer To Look Out For - Some May Differ On Different Skin Tones

Blood cancer: Symptoms explained by healthcare professionals

The Leukaemia Foundation lists 11 symptoms associated with blood cancer, the first of which is unexplained weight loss.

Unexplained weight loss

Unexplained weight loss can be a symptom of blood cancer as cancer cells and the body's reaction to them can alter the body's metabolism and reduce muscle and fat, it explains.

Look out for weight loss that seems unusual based on your current diet and exercise.

Unexplained bruising or bleeding

This can occur with a low level of platelets, which helps blood to clot.

The charity explains: "You may have bleeding from your nose or gums, prolonged bleeding from a cut, heavy periods, or blood in your urine or poo. In very rare cases, there may be a bleed into the brain, which can cause neurological symptoms."

Shortness of breath is considered a common symptom (Image: GETTY)

Petechiae, tiny, upraised red blood spots under the skin, may also occur, often starting on legs. On darker skin, they can show up darker than the skin around them.

Lumps or swellings

These can occur as a result of abnormal white blood cells building in your lymph glands.

The charity advises you are most likely to notice these in your neck, armpit or groin, they are usually pains, although some people find they ache, and if there are lumps or swellings further inside your body, and they person organs such as your lungs, this may cause pain, discomfort or breathlessness.

Shortness of breath

This can be caused by anaemia, which is a low levels of red blood cells. The charity says you may expect breathlessness even when you're resting, feeling faint or lightheaded, and a rapid or irregular heartbeat.

Drenching night sweats

People with lymphoma or leukaemia may experience this, said the charity, although the cause is unknown.

Severe itching can also be a sign (Image: GETTY)

Repeat or severe infections

This can be caused by a low level of white blood cells, which are important for fighting infection.

The charity says you may expect infections that are persistent, recurrent or severe, flu-like symptoms, and mouth ulcers that don't go away.

Regular and frequent fevers

Low levels of white blood cells can be the cause. The charity says you may expect a "fever of 38°C or above even if there aren't any other obvious signs of infection".

Unexplained rash or itchy skin

Rashes can be caused by a low level of platelets, says the charity. It adds: "Some people with blood cancer experience itching, but we don't fully understand what causes this yet."

You may notice small red spots in the skin (petechiae) or a purple rash, known as purpura. Both of these don't face when you press on them.

Itching, when caused by lymphoma, can be severe and may cause a burning sensation, and on darker skin petechiae and purpura can appear darker than the surrounding skin.

Pain in your bone, joints or abdomen

This can be caused by damage to the bones and abnormal blood cells building up in the spleen.

The charity says myeloma can cause pain in any major bones such as your back, ribs or hips, and you may feel full after only eating small amounts, have discomfort under your ribs on the left side, and have bloating or swelling, or occasionally pain.

Fatigue

Fatigue can occur as a result of anaemia. This may also be accompanied by feeling faint and headaches, says the charity.

Unusually pale complexion

This can also occur as a result of anaemia. The charity advises people with darker skin may look greyish with pale palms on their hands. 

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