***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Aims /hypothesisObservational and mechanistic studies have suggested a possible relationship between treatment with metformin and decreased incidence of cancer in participants with type 2 diabetes . We extracted data for malignancies from the ADOPT ( A Diabetes Outcome Progression Trial ) and RECORD ( Rosiglitazone Evaluated for Cardiovascular Outcomes and Regulation of Glycaemia in Diabetes ) r and omised controlled clinical trials , in which the efficacy and /or safety of metformin was assessed in comparison with sulfonylureas and rosiglitazone . Methods Neoplasm occurrences were collected as adverse events in these studies . We review ed and re-analysed the individual participant data in both studies for serious adverse events , malignancies reported as adverse events and related neoplasms of special interest . Results In ADOPT , 50 participants ( 3.4 % ) on  metformin  and 55 ( 3.8 % ) on each of rosiglitazone and glibenclamide ( known as glyburide in the USA and Canada ) developed serious adverse event malignancies ( excluding non-melanoma skin cancers ) . This corresponds to 1.03 , 1.12 and 1.31 per 100 person-years , giving hazard ratios for metformin of 0.92 ( 95 % CI 0.63–1.35 ) vs rosiglitazone and 0.78 ( 0.53–1.14 ) vs glibenclamide . In RECORD , on a background of sulfonylurea , 69 ( 6.1 % ) participants developed malignant neoplasms in the metformin group , compared with 56 ( 5.1 % ) in the rosiglitazone group ( HR 1.22 [ 0.86–1.74 ] ) . On a background of metformin , 74 ( 6.7 % ) participants in the sulfonylurea group developed malignant neoplasms , compared with 57 ( 5.1 % ) in the rosiglitazone group ( HR 1.33 [ 0.94–1.88 ] ) . Conclusions /interpretationThe malignancy rates in these two r and omised controlled clinical trials do not support a view that metformin offers any particular protection against malignancy compared with rosiglitazone . However , they do not refute the possibility of a difference compared with sulfonylureas There is growing evidence that patients with type 2 diabetes mellitus have increased  cancer risk . We examined the association between diabetes , cancer , and cancer-related mortality  and hypothesized that insulin sensitizers lower cancer-related mortality . Participants in the Diabetes Cardiovascular Risk and Evaluation : Targets and Essential Data for Commitment of Treatment study , a nationwide cross-sectional and prospect i ve epidemiological study , were recruited from German primary care practice s. In the cross-sectional study , subjects with type 2 diabetes mellitus had a higher prevalence of malignancies ( 66/1308 , 5.1 % ) compared to nondiabetic subjects ( 185/6211 , 3.0 % ) ( odds ratio , 1.64 ; 95 % confidence interval , 1.12 - 2.41 ) before and after adjustment for age , sex , hemoglobin A(1c ) , smoking status , and body mass index . Patients on  metformin had a lower prevalence of malignancies , comparable with that among nondiabetic patients , whereas those on any other oral combination treatment had a 2-fold higher risk for malignancies even after adjusting for possible confounders ; inclusion of metformin in these regimens decreased the prevalence of malignancies . In the prospect i ve analyses , diabetic patients in general and diabetic patients treated with insulin ( either as monotherapy or in combination with other treatments ) had a 2- and 4-fold , respectively , higher mortality rate than nondiabetic patients , even after adjustment for potential confounders ( incidence of cancer deaths in patients with type 2 diabetes mellitus [ 2.6 % ] vs the incidence of cancer deaths in patients without type 2 diabetes mellitus [ 1.2 % ] ) . Our results suggest that diabetes and medications for diabetes , with the exception of the insulin sensitizer metformin , increase cancer risk and mortality 
    Output:
    
Conclusions Our findings demonstrate that use of metformin was significantly associated with a lower incidence and a better prognosis of ovarian cancer in patients with diabetes .