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Can­cer , also known as a malig­nant tumor or malig­nant neo­plasm, is a group of dis­eases involv­ing abnor­mal cell growth with the poten­tial to invade or spread to oth­er parts of the body. Not all tumors are can­cer­ous; benign tumors do not spread to oth­er parts of the body. Pos­si­ble signs and symp­toms include: a new lump, abnor­mal bleed­ing, a pro­longed cough, unex­plained weight loss, and a change in bow­el move­ments, among oth­ers. While these symp­toms may indi­cate can­cer, they may also occur due to oth­er issues. There are over 100 dif­fer­ent known can­cers that affect humans. Tobac­co use is the cause of about 22% of can­cer deaths. Anoth­er 10% is due to obe­si­ty, a poor diet, lack of phys­i­cal activ­i­ty, and con­sump­tion of ethanol (alco­hol). Oth­er fac­tors include cer­tain infec­tions, expo­sure to ion­iz­ing radi­a­tion, and envi­ron­men­tal pol­lu­tants. In the devel­op­ing world near­ly 20% of can­cers are due to infec­tions such as hepati­tis B, hepati­tis C, and human papil­lo­mavirus. These fac­tors act, at least part­ly, by chang­ing the genes of a cell. Typ­i­cal­ly many such genet­ic changes are required before can­cer devel­ops. Approx­i­mate­ly 5–10% of can­cers are due to genet­ic defects inher­it­ed from a per­son­’s par­ents. Can­cer can be detect­ed by cer­tain signs and symp­toms or screen­ing tests. It is then typ­i­cal­ly fur­ther inves­ti­gat­ed by med­ical imag­ing and con­firmed by biop­sy. Many can­cers can be pre­vent­ed by not smok­ing, main­tain­ing a healthy weight, not drink­ing too much alco­hol, eat­ing plen­ty of veg­eta­bles, fruits and whole grains, being vac­ci­nat­ed against cer­tain infec­tious dis­eases, not eat­ing too much red meat, and avoid­ing too much expo­sure to sun­light. Ear­ly detec­tion through screen­ing is use­ful for cer­vi­cal and col­orec­tal can­cer. The ben­e­fits of screen­ing in breast can­cer are con­tro­ver­sial. Can­cer is often treat­ed with some com­bi­na­tion of radi­a­tion ther­a­py, surgery, chemother­a­py, and tar­get­ed ther­a­py. Pain and symp­tom man­age­ment are an impor­tant part of care. Pal­lia­tive care is par­tic­u­lar­ly impor­tant in those with advanced dis­ease. The chance of sur­vival depends on the type of can­cer and extent of dis­ease at the start of treat­ment. In chil­dren under 15 at diag­no­sis the five year sur­vival rate in the devel­oped world is on aver­age 80%. For can­cer in the Unit­ed States the aver­age five year sur­vival rate is 66%. In 2012 about 14.1 mil­lion new cas­es of can­cer occurred glob­al­ly (not includ­ing skin can­cer oth­er than melanoma). It caused about 8.2 mil­lion deaths or 14.6% of all human deaths. The most com­mon types of can­cer in males are lung can­cer, prostate can­cer, col­orec­tal can­cer, and stom­ach can­cer, and in females, the most com­mon types are breast can­cer, col­orec­tal can­cer, lung can­cer, and cer­vi­cal can­cer. If skin can­cer oth­er than melanoma were includ­ed in total new can­cers each year it would account for around 40% of cas­es. In chil­dren, acute lym­phoblas­tic leukaemia and brain tumors are most com­mon except in Africa where non-Hodgkin lym­phoma occurs more often. In 2012, about 165,000 chil­dren under 15 years of age were diag­nosed with can­cer. The risk of can­cer increas­es sig­nif­i­cant­ly with age and many can­cers occur more com­mon­ly in devel­oped coun­tries. Rates are increas­ing as more peo­ple live to an old age and as lifestyle changes occur in the devel­op­ing world. The finan­cial costs of can­cer have been esti­mat­ed at $1.16 tril­lion US dol­lars per year as of 2010.