Radiation therapy is used in about half of cases. Radiation can come either from internal sources (brachytherapy) or from external sources. Radiation is most often low-energy X-rays used to treat skin cancer, while higher-energy X-rays are used for cancers in the body. [182] Radiation therapy is usually used in addition to surgery and/or chemotherapy. For some cancers, such as early head and neck cancer, it can be used alone. [183] For painful bone metastases, it has been shown to be effective in about 70% of patients. [183] Non-ionizing radiofrequency radiation from mobile phones, electrical power transmission and other similar sources has been described as a possible carcinogen by the World Health Organization`s International Agency for Research on Cancer. [69] However, the evidence did not support any concerns. [70] [63] This includes that studies have not found a consistent link between mobile phone radiation and cancer risk. [71] Cancer is the second leading cause of death worldwide, accounting for approximately 9.6 million deaths, or one in six deaths, in 2018. Cancers of the lung, prostate, colon, stomach and liver are the most common cancers in men, while breast, colon, lung, cervical and thyroid cancers are the most common in women. Survival is worse in developing countries[24], in part because the most common cancers are more difficult to treat than those associated with developed countries.
[196] In normal cells, tumor suppressor genes prevent cancer by slowing or stopping cell growth. DNA changes that inactivate tumor suppressor genes can lead to uncontrolled cell growth and cancer. But many people with cancer have no symptoms. For these people, cancer is diagnosed during a medical test for another problem or condition. Management ranges from cryotherapy or laser therapy for low-grade intraepithelial squamous light ions, to conization for in situ carcinomas and hysterectomy for pre-invasive cervical cancer in women who do not plan to have children. Management of stage-stage invasive cervical cancer includes radiation therapy and/or hysterectomy. More than 30% of cancer deaths could be prevented by avoiding risk factors such as tobacco, overweight/obesity, poor diet, physical inactivity, alcohol, sexually transmitted infections and air pollution. [125] In addition, poverty could be considered an indirect risk factor for human cancer. [126] Not all environmental causes are manageable, such as natural background radiation and cancers caused by inherited genetic disorders, and are therefore not preventable by personal behavior.
Cells of the immune system can recognize and attack cancer cells. But some cancer cells can evade detection or thwart an attack. Some cancer treatments can help the immune system better recognize and kill cancer cells. Several national medical guidelines recommend early palliative care for patients whose cancer has caused distressing symptoms or who need help managing their disease. In patients who have been diagnosed with metastatic disease for the first time, palliative care may be indicated immediately. Palliative care is indicated for patients with a prognosis of less than 12 months of life, even if treated aggressively. [186] [187] [188] In the early stages, the patient may sometimes experience pain in the back or in the epigastric or retrosternal region, which is relieved by over-the-counter painkillers. As the tumor grows, the patient may notice a vague feeling of fullness, heaviness and abdominal stretching after meals. Depending on the progression of the cancer, the patient may report weight loss due to appetite disorders; nausea; and vomiting.
Dysphagia and ground coffee can occur if the tumor is in the cardia and bleeds slowly. Weakness and fatigue are common. Because early symptoms include chronic dyspepsia and epigastric discomfort, patients may self-medicate with over-the-counter antacids or histamine blockers, delay prescribed treatments, and allow cancer to progress. Diagnosis can be suggested by the results of digital rectal examination, anoscopy, flexible or rigid sigmoidoscopy, colonoscopy, virtual colonoscopy or barium enema examination. It is confirmed by biopsy of suspicious lesions. Prevention includes screening asymptomatic men and women at medium risk from the age of 50, annual occult blood tests at home (over a period of three days) and colonoscopy every 10 years.
