The epidemiology of depression showed that the rates are high. For example, the World Mental HealthSurvey, an epidemiologic community study conducted in 28 countries, found a life-time prevalence rate thatranged from 3.3 % in Nigeria to 21.4% % in the US. With regard to persons with cancer, 12.5% of a sample ofover 17,000 respondents over the age of 50 of a US survey of community-dwelling adults found that people thatreported they had cancer had higher risk of fatigue (OR =1.5 95% CI 1.3-1.6); depression (OR=1.2, 95% CI 1.1-1.4) and pain (OR =1.2, 95% CI 1.03-1.3.).The rate of depression seems to be differently associated with cancersite. For example: It is higher in pancreatic cancer (33%-50%) and lung (11%-44%), and it is lower in lymphoma(8%-19%) and colon (13% and 25%). For breast cancer –likely the most studied cancer site- the prevalenceranges from 1.5% to 46%. Ciaramelli and Poli (2001) found that depressed persons had more pain and metastasisthan the non-depressed but no more lifetime depression that the non-depressed. In terminally patients, studieshave found that the higher the level of disability the higher the rates of depression. Interestingly, while almost allstudies of depression in the community found higher rates in women than in men - this is far from the ruleamong persons with cancer. Despite the marked burden and the existence of effective treatment, a very largeproportion of the persons with depression remain untreated. The causes to be imputed for the treatment gapare of different nature. Some of these causes are related to the suffering person, to the social context and to thehealth system. Often, the treating physicians fail to identify depression and to treat it properly. For example, inone evaluation of 456 outpatients with solid tumors a minority (14%) of the depressed were identified as such.Why is it important to assess depression in persons with cancer? Untreated depression both enhances the risksto life and it lowers the quality of life. It may be associated to a reduced chance of survival in women with earlystage breast cancer. One possible reason is limited adherence to the treatment plan. Timely identification andwell prescribed and conducted treatment could make a substantial difference.