About 20 percent of primary tumors of the heart are malignant in nature. Malignant tumors of the heart include rhabdomyosarcomas, angiosarcomas, myxosarcomas, fibrosarcomas, leiomyosarcomas, reticulum cell sarcomas, desmoplastic small round cell tumor, and liposarcomas. The cardiac sarcomas may occur at any age, but are more commonly seen in individuals in their 20s to 40s. They occur equally in males and females.

The vast majority of the tumors of the heart have a benign course and are not directly fatal. However, even the benign tumors of the heart can be lethal due to either direct extension into the electrical conduction system of the heart (causing complete heart block or a fatal dysrhythmia), or due to emboli from the tumor mass that may have lethal sequelae.

The malignant tumors of the heart have a worse prognosis. Cardiac sarcomas generally lead to death within 2 years of diagnosis, due to rapid infiltration of the myocardium of the heart and obstruction of the normal flow of blood within the heart.

Adult survivors of childhood cancer have some physical, psychological, and social difficulties.

Premature heart disease is a major long-term complication in adult survivors of childhood cancer. Adult survivors are eight times more likely to die of heart disease than other people, and more than half of children treated for cancer develop some type of cardiac abnormality, although this may be asymptomatic or too mild to qualify for a clinical diagnosis of heart disease.

Factors that contribute to the development of hypopharyngeal cancer include:

- Smoking

- Chewing tobacco

- Heavy alcohol use

- Poor diet

Smoking, like lung cancer, can cause hypopharyngeal cancer because it contains carcinogens that alter the DNA or RNA in a dividing cell. These alterations may change a normal DNA sequence to an oncogene, a gene that causes cancer after exposure to a carcinogen.

Squamous cells, a type of cell that lines hollow organs like the throat, mouth, lungs, and outer layer of skin, are particularly vulnerable when exposed to cigarette smoke.

Chewing tobacco can have the same effects as smoking and is also linked to hypopharyngeal cancer. The chewing tobacco is placed into the mouth, leaving it exposed to enzymes, like amylase, which partly digests the carcinogenic material. Saliva is swallowed, along with the cancer-promoting material, which passes through the hypopharynx on its way to the esophagus.

Heavy alcohol use is linked to Hypopharyngeal Cancer as well. Alcohol damages the lining of the hypopharynx, increasing the amount of chemicals that are allowed to seep into the underlying membranes. Heavy alcohol use is also associated with nutritional deficiencies.

A disease called Plummer-Vinson syndrome, a genetic disorder that causes a long-term iron deficiency, may also lead to Hypopharyngeal Cancer. Other factors like a deficiency in certain vitamins also appear to contribute to this type of cancer.

Smoking tobacco appears to increase the risk of breast cancer, with the greater the amount smoked and the earlier in life that smoking began, the higher the risk. In those who are long-term smokers, the risk is increased 35% to 50%. A lack of physical activity has been linked to about 10% of cases. Sitting regularly for prolonged periods is associated with higher mortality from breast cancer. The risk is not negated by regular exercise, though it is lowered.

There is an association between use of hormonal birth control and the development of premenopausal breast cancer, but whether oral contraceptives use may actually cause premenopausal breast cancer is a matter of debate. If there is indeed a link, the absolute effect is small. Additionally, it is not clear if the association exists with newer hormonal birth controls. In those with mutations in the breast cancer susceptibility genes "BRCA1" or "BRCA2", or who have a family history of breast cancer, use of modern oral contraceptives does not appear to affect the risk of breast cancer.

The association between breast feeding and breast cancer has not been clearly determined; some studies have found support for an association while others have not. In the 1980s, the abortion–breast cancer hypothesis posited that induced abortion increased the risk of developing breast cancer. This hypothesis was the subject of extensive scientific inquiry, which concluded that neither miscarriages nor abortions are associated with a heightened risk for breast cancer.

A number of dietary factors have been linked to the risk for breast cancer. Dietary factors which may increase risk include a high fat diet, high alcohol intake, and obesity-related high cholesterol levels. Dietary iodine deficiency may also play a role. Evidence for fiber is unclear. A 2015 review found that studies trying to link fiber intake with breast cancer produced mixed results. In 2016 a tentative association between low fiber intake during adolescence and breast cancer was observed.

Other risk factors include radiation and shift-work. A number of chemicals have also been linked, including polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and organic solvents Although the radiation from mammography is a low dose, it is estimated that yearly screening from 40 to 80 years of age will cause approximately 225 cases of fatal breast cancer per million women screened.

Cancer prevention is defined as active measures to decrease cancer risk. The vast majority of cancer cases are due to environmental risk factors. Many of these environmental factors are controllable lifestyle choices. Thus, cancer is generally preventable. Between 70% and 90% of common cancers are due to environmental factors and therefore potentially preventable.

Greater than 30% of cancer deaths could be prevented by avoiding risk factors including: tobacco, excess weight/obesity, poor diet, physical inactivity, alcohol, sexually transmitted infections and air pollution. Not all environmental causes are controllable, such as naturally occurring background radiation and cancers caused through hereditary genetic disorders and thus are not preventable via personal behavior.

Children with cancer are at risk for developing various cognitive or learning problems. These difficulties may be related to brain injury stemming from the cancer itself, such as a brain tumor or central nervous system metastasis or from side effects of cancer treatments such as chemotherapy and radiation therapy. Studies have shown that chemo and radiation therapies may damage brain white matter and disrupt brain activity.

Risk factors can be divided into two categories:

- "modifiable" risk factors (things that people can change themselves, such as consumption of alcoholic beverages), and

- "fixed" risk factors (things that cannot be changed, such as age and biological sex).

The primary risk factors for breast cancer are being female and older age. Other potential risk factors include genetics, lack of childbearing or lack of breastfeeding, higher levels of certain hormones, certain dietary patterns, and obesity. Recent studies have indicated that exposure to light pollution is a risk factor for the development of breast cancer.

Idiopathic giant-cell myocarditis (IGCM) is a cardiovascular disease of the muscle of the heart (myocardium).

The condition is rare; however, it is often fatal and there is no proven cure because of the unknown nature of the disorder.

IGCM frequently leads to death with a high rate of about 70% in first year. A patient with IGCM typically presents with symptoms of heart failure, although some may present initially with ventricular arrhythmia or heart block. Median age from the time the disease is diagnosed to the time of death is approximately 6 months. 90% of patients are either deceased by the end of 1 year or have received a heart transplant. Diagnosis is made by endomyocardial biopsy during heart catheterization. Biopsy shows multinucleated giant cells and thus the name. While previously cases universally required heart transplantation, recent studies show that two thirds of patients can survive past one year with high doses of immunosuppressants such as prednisone and cyclosporine. The transplanted heart has a high chance of disease recurrence. Compared to lymphocytic (presumed viral) myocarditis, giant cell myocarditis is much more severe with much more rapid progression.

It is suggested to be caused by T-lymphocytes.

HIV is a major cause of cardiomyopathy – in particular dilated cardiomyopathy. Dilated cardiomyopathy can be due to pericardial effusion or infective endocarditis, especially in intravenous drug users which are common in the HIV population. However, the most researched causes of cardiomyopathy are myocardial inflammation and infection caused by HIV-1. Toxoplasma gondii is the most common opportunistic infectious agent associated with myocarditis in AIDS. Coinfection with viruses (usually, coxsackievirus B3 and cytomegalovirus) seems to have an important affect in myocarditis. HIV-1 infection produces additional virus and cytokines such as TNF-α. This induces cardiomyocyte apoptosis. TNF-α causes a negative inotropic effect by interfering with the intracellular calcium ion concentrations. The intensity of the stains for TNF-α and iNOS of the myocardium was greater in patients with HIV associated cardiomyopathy, myocardial viral infection and was inversely correlated with CD4 count with antiretroviral therapy having no effect. Cardiac autoimmunity affects the pathogenesis of HIV-related heart disease as HIV-infected patients with dilated cardiomyopathy are more likely to have cardiac-specific autoantibodies than HIV-infected patients with healthy hearts and HIV-negative controls. Many patients with HIV have nutritional deficiencies which have been linked to left ventricular dysfunction. HIV-infected patients with encephalopathy are more likely to die of congestive heart failure than are those without encephalopathy. HAART has reduced the incidence of myocarditis thus reducing the prevalence of HIV-associated cardiomyopathy. Intravenous immunoglobulins (IVIGs) can also help patients with HIV-associated myocarditis.

Diet, physical inactivity and obesity are related to up to 30–35% of cancer deaths. In the United States excess body weight is associated with the development of many types of cancer and is a factor in 14–20% of cancer deaths. A UK study including data on over 5 million people showed higher body mass index to be related to at least 10 types of cancer and responsible for around 12,000 cases each year in that country. Physical inactivity is believed to contribute to cancer risk, not only through its effect on body weight but also through negative effects on the immune system and endocrine system. More than half of the effect from diet is due to overnutrition (eating too much), rather than from eating too few vegetables or other healthful foods.

Some specific foods are linked to specific cancers. A high-salt diet is linked to gastric cancer. Aflatoxin B1, a frequent food contaminant, causes liver cancer. Betel nut chewing can cause oral cancer. National differences in dietary practices may partly explain differences in cancer incidence. For example, gastric cancer is more common in Japan due to its high-salt diet while colon cancer is more common in the United States. Immigrant cancer profiles develop mirror that of their new country, often within one generation.

Zidovudine is an example of a nucleoside analogue and has been shown to cause: myocarditis and dilated cardiomyopathy as well as an increase in total cholesterol, triglycerides, LDL, HDL and insulin resistance. Protease inhibitors are another group of drugs (e.g. ritonavir) and some of them can cause a range of problems such as: lipodystrophy, atherosclerosis, increase total cholesterol, triglyceride, HDL, LDL, and insulin resistance. Amphotericin B can cause dilated cardiomyopathy, hypertension and bradycardia whereas, Ganciclovir can cause ventricular tachycardia. Interferon-alpha can cause arrhythmia and myocardial infarction/ischemia.

In some population studies moderate alcohol consumption is associated with increase the breast cancer risk.

In contrast, research by the Danish National Institute for Public Health, comprising 13,074 women aged 20 to 91 years, found that moderate drinking had virtually no effect on breast cancer risk.

Studies that control for screening incidence show no association with moderate drinking and breast cancer, e.g.. Moderate drinkers tend to screen more which results in more diagnoses of breast cancer, including mis-diagnoses. A recent study of 23 years of breast cancer screening in the Netherlands concluded that 50% of diagnoses were over-diagnoses.

Some therapies for other forms of cancer increase the lifetime risk of endometrial cancer, which is a baseline 2–3%. Tamoxifen, a drug used to treat estrogen-positive breast cancers, has been associated with endometrial cancer in approximately 0.1% of users, particularly older women, but the benefits for survival from tamoxifen generally outweigh the risk of endometrial cancer. A one to two-year course of tamoxifen approximately doubles the risk of endometrial cancer, and a five-year course of therapy quadruples that risk. Raloxifene, a similar drug, did not raise the risk of endometrial cancer. Previously having ovarian cancer is a risk factor for endometrial cancer, as is having had previous radiotherapy to the pelvis. Specifically, ovarian granulosa cell tumors and thecomas are tumors associated with endometrial cancer.

Low immune function has also been implicated in endometrial cancer. High blood pressure is also a risk factor, but this may be because of its association with obesity. Sitting regularly for prolonged periods is associated with higher mortality from endometrial cancer. The risk is not negated by regular exercise, though it is lowered.

Studies suggest that drinking alcohol during pregnancy may affect the likelihood of breast cancer in daughters. "For women who are pregnant, ingestion of alcohol, even in moderation, may lead to elevated circulating oestradiol levels, either through a reduction of melatonin or some other mechanism. This may then affect the developing mammary tissue such that the lifetime risk of breast cancer is raised in their daughters."

While some dietary factors have been associated with prostate cancer the evidence is still tentative. Evidence supports little role for dietary fruits and vegetables in prostate cancer occurrence. Red meat and processed meat also appear to have little effect in human studies. Higher meat consumption has been associated with a higher risk in some studies.

Lower blood levels of vitamin D may increase the risk of developing prostate cancer.

Folic acid supplements have no effect on the risk of developing prostate cancer.

Smoking and the use of progestin are both protective against endometrial cancer. Smoking provides protection by altering the metabolism of estrogen and promoting weight loss and early menopause. This protective effect lasts long after smoking is stopped. Progestin is present in the combined oral contraceptive pill and the hormonal intrauterine device (IUD). Combined oral contraceptives reduce risk more the longer they are taken: by 56% after four years, 67% after eight years, and 72% after twelve years. This risk reduction continues for at least fifteen years after contraceptive use has been stopped. Obese women may need higher doses of progestin to be protected. Having had more than five infants (grand multiparity) is also a protective factor, and having at least one child reduces the risk by 35%. Breastfeeding for more than 18 months reduces risk by 23%. Increased physical activity reduces an individual's risk by 38–46%. There is preliminary evidence that consumption of soy is protective.

A number of medications may cause or worsen the disease. This includes NSAIDS, a number of anesthetic agents such as ketamine, thiazolidinediones, a number of cancer medications, salbutamol, and tamsulosin among others.

Chronic stable heart failure may easily decompensate. This most commonly results from an intercurrent illness (such as myocardial infarction (a heart attack), pneumonia), abnormal heart rhythms, uncontrolled hypertension, or a patient's failure to maintain a fluid restriction, diet, or medication. Other well recognized factors that may worsen CHF include the following: anemia and hyperthyroidism which place additional strain on the heart muscle, excessive fluid or salt intake, and medication that causes fluid retention such as NSAIDs and thiazolidinediones. NSAIDs in general increase the risk twofold.

Symptoms of Hypopharyngeal Cancer include:

- Swollen lymph nodes in the neck (first sign of a problem in half of all patients)

- Sore throat in one location that persists after treatment

- Pain that radiates from the throat to the ears

- Difficult or painful swallowing (often leads to malnutrition and weight loss because of a refusal to eat)

- Voice changes (late stage cancer)

Although the disease is more common in African-Americans than in Caucasians, it may occur in any patient population.

There are also some links between prostate cancer and medications, medical procedures, and medical conditions. Use of the cholesterol-lowering drugs known as the statins may also decrease prostate cancer risk.

Infection or inflammation of the prostate (prostatitis) may increase the chance for prostate cancer while another study shows infection may help prevent prostate cancer by increasing blood flow to the area. In particular, infection with the sexually transmitted infections chlamydia, gonorrhea, or syphilis seems to increase risk. Finally, obesity and elevated blood levels of testosterone may increase the risk for prostate cancer. There is an association between vasectomy and prostate cancer; however, more research is needed to determine if this is a causative relationship.

Research released in May 2007, found that US war veterans who had been exposed to Agent Orange had a 48% increased risk of prostate cancer recurrence following surgery.

Although in many cases no cause is apparent, dilated cardiomyopathy is probably the result of damage to the myocardium produced by a variety of toxic, metabolic, or infectious agents. It may be due to fibrous change of the myocardium from a previous myocardial infarction. Or, it may be the late sequelae of acute viral myocarditis, such as with Coxsackie B virus and other enteroviruses possibly mediated through an immunologic mechanism.

Other causes include:

- Chagas disease, due to "Trypanosoma cruzi". This is the most common infectious cause of dilated cardiomyopathy in Latin America

- Pregnancy. Dilated cardiomyopathy occurs late in gestation or several weeks to months postpartum as a peripartum cardiomyopathy. It is reversible in half of cases.

- Alcohol abuse (alcoholic cardiomyopathy)

- Nonalcoholic toxic insults include administration of certain chemotherapeutic agents, in particular doxorubicin (Adriamycin), and cobalt.

- Thyroid disease

- Inflammatory diseases such as sarcoidosis and connective tissue diseases

- Tachycardia-induced cardiomyopathy

- Muscular dystrophy

- Tuberculosis - 1 to 2% of TB cases.

- Autoimmune mechanisms

Recent studies have shown that those subjects with an extremely high occurrence (several thousands a day) of premature ventricular contractions (extrasystole) can develop dilated cardiomyopathy. In these cases, if the extrasystole are reduced or removed (for example, via ablation therapy) the cardiomyopathy usually regresses.

The exact incidence of myocarditis is unknown. However, in series of routine autopsies, 1–9% of all patients had evidence of myocardial inflammation. In young adults, up to 20% of all cases of sudden death are due to myocarditis.

Among patients with HIV, myocarditis is the most common cardiac pathological finding at autopsy, with a prevalence of 50% or more.

A large number of causes of myocarditis have been identified, but often a cause cannot be found. In Europe and North America, viruses are common culprits. Worldwide, however, the most common cause is Chagas' disease, an illness endemic to Central and South America that is due to infection by the protozoan "Trypanosoma cruzi". Many of the causes listed below, particularly those involving protozoa, fungi, parasites, allergy, autoimmune disorders, and drugs are also causes of eosinophilic myocarditis.