cancer Prognosis

Prognosis

See also: List of cancer mortality rates in the United States and Cancer survivor

Cancer has a reputation as a deadly disease. Taken as a whole, about half of people receiving treatment for invasive cancer (excluding carcinoma in situ and non-melanoma skin cancers) die from cancer or its treatment.^[19] Survival is worse in the developing world,^[19] partly because the types of cancer that are most common there are at present harder to treat than those associated with the lifestyle of developed countries.^[148] However, the survival rates vary dramatically by type of cancer, and by the stage at which it is diagnosed, with the range running from the great majority of people surviving to almost no one surviving as long as five years after diagnosis. Once a cancer has metastasized or spread beyond its original site, the prognosis normally becomes much worse.

Those who survive cancer are at increased risk of developing a second primary cancer at about twice the rate of those never diagnosed with cancer.^[149] The increased risk is believed to be primarily due to the same risk factors that produced the first cancer, partly due to the treatment for the first cancer, and potentially related to better compliance with screening.^[149]

Predicting either short-term or long-term survival is difficult and depends on many factors. The most important factors are the particular kind of cancer and the patient's age and overall health. People who are frail with many other health problems have lower survival rates than otherwise healthy people. A centenarian is unlikely to survive for five years even if the treatment is successful. People who report a higher quality of life tend to survive longer.^[150] People with lower quality of life may be affected by major depressive disorder and other complications from cancer treatment and/or disease progression that both impairs their quality of life and reduces their quantity of life. Additionally, patients with worse prognoses may be depressed or report a lower quality of life directly because they correctly perceive that their condition is likely to be fatal.

People with cancer, even those who are walking on their own, have an increased risk of blood clots in veins. The use of heparin appears improve survival and decrease the risk of blood clots.^[151]

Epidemiology

Main article: Epidemiology of cancer

See also: List of countries by cancer rate

Death rate adjusted for age for malignant cancer per 100,000 inhabitants in 2004^[152]

no data   ≤ 55   55–80   80–105   105–130   130–155   155–180

180–205   205–230   230–255   255–280   280–305   ≥ 305

In 2008, approximately 12.7 million cancers were diagnosed (excluding non-melanoma skin cancers and other non-invasive cancers),^[19]and in 2010 nearly 7.98 million people died.^[153] Cancers as a group account for approximately 13% of all deaths each year with the most common being: lung cancer (1.4 million deaths), stomach cancer (740,000 deaths), liver cancer (700,000 deaths), colorectal cancer(610,000 deaths), and breast cancer (460,000 deaths).^[154] This makes invasive cancer the leading cause of death in the developed worldand the second leading cause of death in the developing world.^[19] Over half of cases occur in the developing world.^[19]

Deaths from cancer were 5.8 million in 1990^[153] and rates have been increasing primarily due to an aging population and lifestyle changes in the developing world.^[19] The most significant risk factor for developing cancer is old age.^[155] Although it is possible for cancer to strike at any age, most people who are diagnosed with invasive cancer are over the age of 65.^[155] According to cancer researcherRobert A. Weinberg, "If we lived long enough, sooner or later we all would get cancer."^[156] Some of the association between aging and cancer is attributed to immunosenescence,^[157] errors accumulated in DNA over a lifetime,^[158] and age-related changes in the endocrine system.^[159] The effect of aging on cancer is complicated with a number of factors such as DNA damage and inflammation promoting it and a number of factors such as vascular aging and endocrine changes inhibiting it.^[160]

Some slow-growing cancers are particularly common. Autopsy studies in Europe and Asia have shown that up to 36% of people have undiagnosed and apparently harmless thyroid cancer at the time of their deaths, and that 80% of men develop prostate cancer by age 80.^[161][162] As these cancers did not cause the person's death, identifying them would have represented overdiagnosis rather than useful medical care.

The three most common childhood cancers are leukemia (34%), brain tumors (23%), and lymphomas (12%).^[163] In the United States cancer affects about 1 in 285 children.^[164]Rates of childhood cancer have increased by 0.6% per year between 1975 to 2002 in the United States^[165] and by 1.1% per year between 1978 and 1997 in Europe.^[163] Death from childhood cancer have decreased by half since 1975 in the United States.^[164]