Insulin therapy and risk of prostate cancer: a systematic review and meta-analysis of observational studies

Prostate cancer genetic propensity risk score may modify the association between this tumour and type 2 diabetes mellitus (MCC-Spain study)

BACKGROUND

Some studies have reported an inverse association between type 2 diabetes mellitus (T2DM) and prostate cancer (PCa), but results on this issue are still inconsistent. In this study, we evaluate whether this heterogeneity might be related to differences in this relationship by tumour or by individual genetic susceptibility to PCa.

METHODS

We studied 1047 incident PCa cases and 1379 randomly selected controls, recruited in 7 Spanish provinces for the population-based MCC-Spain case-control. Tumour were classified by aggressiveness according to the International Society of Urological Pathology (ISUP), and we constructed a PCa polygenic risk score (PRS) as proxy for genetic susceptibility. The epidemiological questionnaire collected detailed self-reported data on T2DM diagnosis and treatment. The association between T2DM status and PCa was studied by fitting mixed logistic regression models, and, for its association by aggressiveness of PCa, with multinomial logistic regression models. To evaluate the possible modulator role of PRS in this relationship, we included the corresponding interaction term in the model, and repeated the analysis stratified by PRS tertiles.

RESULTS

Globally, our results showed an inverse association between T2DM and overall PCa limited to grade 1 tumours (OR_ISUP = 1: 0.72; 95% CI: 0.53-0.98), which could be compatible with a detection bias. However, PCa risk also varied with duration of diabetes treatment -inversely to metformin and positively with insulin-, without differences by aggressiveness. When we considered genetic susceptibility, T2DM was more strongly associated with lower PCa risk in those with lower PRS (OR_{tertile 1}: 0.31; 95% CI: 0.11-0.87), independently of ISUP grade.

CONCLUSIONS

Our findings reinforce the need to include aggressiveness and susceptibility of PCa, and T2DM treatments in the study of the relationship between both diseases.

The Influence of Anti-Diabetic Drugs on Prostate Cancer

The incidences of prostate cancer (PC) and diabetes are increasing, with a sustained trend. The occurrence of PC and type 2 diabetes mellitus (T2DM) is growing with aging. The correlation between PC occurrence and diabetes is noteworthy, as T2DM is correlated with a reduced risk of incidence of prostate cancer. Despite this reduction, diabetes mellitus increases the mortality in many cancer types, including prostate cancer. The treatment of T2DM is based on lifestyle changes and pharmacological management. Current available drugs, except insulin, are aimed at increasing insulin secretion (sulfonylureas, incretin drugs), improving insulin sensitivity (biguanides, thiazolidinediones), or increasing urinary glucose excretion (gliflozin). Comorbidities should be taken into consideration during the treatment of T2DM. This review describes currently known information about the mechanism and impact of commonly used antidiabetic drugs on the incidence and progression of PC. Outcomes of pre-clinical studies are briefly presented and their correlations with available clinical trials have also been observed. Available reports and meta-analyses demonstrate that most anti-diabetic drugs do not increase the risk during the treatment of patients with PC. However, some reports show a potential advantage of treatment of T2DM with specific drugs. Based on clinical reports, use of metformin should be considered as a therapeutic option. Moreover, anticancer properties of metformin were augmented while combined with GLP-1 analogs.

Association of type 2 diabetes mellitus and antidiabetic medication with risk of prostate cancer: a population-based case-control study

BACKGROUND

Prostate cancer (PCa) and type 2 diabetes mellitus (T2DM) are prevalent conditions that often occur concomitantly. However, many aspects of the impact of T2DM, particularly the duration of T2DM and antidiabetic medications, on PCa risk are poorly understood.

METHODS

To assess the association of duration of T2DM and antidiabetic medication with PCa risk, we designed a matched case-control study, including 31,415 men with PCa and 154,812 PCa-free men in Prostate Cancer data Base Sweden (PCBaSe) 4.1.

RESULTS

Overall, a decreased risk of PCa was observed for men with T2DM (odds ratio (OR): 0.81, 95% confidence interval (CI): 0.78-0.84), as compared to men without T2DM. The decreased risk of PCa was consistently showed across duration of T2DM. With respect to use of antidiabetic drugs, this inverse association with duration was also found for all medications types, as compared to men without T2DM, including insulin, metformin and sulphonylurea (SU) (e.g. 3- < 5 yr insulin OR:0.69, 95%CI:0.60-0.80; 3- < 5 yr metformin OR: 0.82, 95%CI: 0.74-0.91; 3- < 5 yr SU OR: 0.72, 95%CI: 0.62-0.83). When stratifying by PCa risk categories, this decreased risk was most evident for diagnosis of low and intermediate-risk PCa (low-risk OR: 0.65, 95%CI: 0.66-0.70, intermediate-risk OR: 0.80, 95%CI: 0.75-0.85).

CONCLUSIONS

The study showed an inverse association between pre-existing T2DM and PCa across different durations of T2DM and all types of T2DM medication received. This inverse association was most evident for low- and intermediate-risk PCa, suggesting that whilst T2DM and its medication may protect some men from developing PCa, the relationship warrants further study.

Antidiabetic drugs influence molecular mechanisms in prostate cancer

Background: We investigated the role of diabetes mellitus (DM) and the molecular mechanisms of antidiabetic drugs in prostate cancer (PCa).

Patients and Methods: 167 patients with both DM and PCa underwent radical prostatectomy (RPE). We divided our patient collective into “metformin” users, “insulin” users, “other antidiabetic drug” users and those with “no antidiabetic drug/diet only” (control group) and analyzed differences in PCa aggressiveness and laboratory parameters among treatment groups. In addition, we generated a tissue-micro-array (TMA) from RPE specimens for the analysis of candidate target pathways of antidiabetic drugs by immunohistochemistry (IHC).

Results: Gleason score of both biopsy and RPE, biopsy undergrading, tumor stage as well as positive resection margins did not significantly change among groups. Preoperative body mass-index, PSA, fPSA and prostate volume/weight did not change among the treatment groups. As well, CRP, GOT, GPT, yGT, LDH, amylase, hemoglobin, TSH, FT3 and FT4 did not differ. Metformin or insulin use was not associated with changes in biochemical tumor recurrence or PCa specific mortality rates. However, tissue TMA analyses by IHC showed decreased mTOR activation, as indicated by phospho-mTOR in cancer tissue of patients with metformin and also with insulin use compared to the control group. In addition, we were able to show that the androgen receptor and the epithelial-cell contact marker E-cadherin decreased upon metformin use compared to the control group.

Conclusion: We did not find a connection between antidiabetic drugs and PCa aggressiveness or progression. However, tumor biology seems to be different among patients with and without antidiabetic drugs.

Prospective study of Type 2 diabetes mellitus, anti-diabetic drugs and risk of prostate cancer

Type 2 diabetes mellitus (T2DM) has consistently been associated with decreased risk of prostate cancer; however, if this decrease is related to the use of anti-diabetic drugs is unknown. We prospectively studied men in the comparison cohort in the Prostate Cancer data Base Sweden 3.0, with data on T2DM, use of metformin, sulfonylurea and insulin retrieved from national health care registers and demographic databases. Cox proportional hazards regression models were used to compute hazard ratios (HR) and 95% confidence intervals (CI) of prostate cancer, adjusted for confounders. The study consisted of 612,846 men, mean age 72 years (standard deviation; SD = 9 years), out of whom 25,882 men were diagnosed with prostate cancer during follow up, mean time of 5 years (SD = 3 years). Men with more than 1 year's duration of T2DM had a decreased risk of prostate cancer compared to men without T2DM (HR = 0.85, 95% CI = 0.82-0.88) but among men with T2DM, those on metformin had no decrease (HR = 0.96, 95% CI = 0.77-1.19), whereas men on insulin (89%) or sulfonylurea (11%) had a decreased risk (HR = 0.73, 95% CI = 0.55-0.98), compared to men with T2DM not on anti-diabetic drugs. Men with less than 1 year's duration of T2DM had no decrease in prostate cancer risk (HR = 1.11, 95% CI = 0.95-1.31). Our results gave no support to the hypothesis that metformin protects against prostate cancer as recently proposed. However, our data gave some support to an inverse association between T2DM severity and prostate cancer risk.

Prostate Cancer Patients With Unmanaged Diabetes or Receiving Insulin Experience Inferior Outcomes and Toxicities After Treatment With Radiation Therapy

BACKGROUND

The purpose of the study was to determine the effect of type 2 diabetes mellitus (T2DM) on outcomes and toxicities among men with localized prostate cancer receiving definitive radiation therapy.

PATIENTS AND METHODS

We performed a retrospective review of 3217 patients, from 1998 to 2013, subdivided into 5 subgroups: (I) no T2DM; (II) T2DM receiving oral antihyperglycemic agent that contains metformin, no insulin; (III) T2DM receiving nonmetformin oral agent alone, no insulin; (IV) T2DM receiving any insulin; and (V) T2DM not receiving medication. Outcome measures were overall survival, freedom from biochemical failure (BF), freedom from distant metastasis, cancer-specific survival, and toxicities. Kaplan-Meier analysis, log rank tests, Fine and Gray competing risk regression (to adjust for patient and lifestyle factors), Cox models, and subdistribution hazard ratios (sHRs) were used.

RESULTS

Of the 3217 patients, 1295 (40%) were low-risk, 1192 (37%) were intermediate-risk, and 652 (20%) were high risk. The group I to V distribution was 81%, 8%, 5%, 3%, and 4%. The median dose was 78 Gy, and the median follow-up time was 50 (range, 1-190) months. Group V had increased mortality (sHR, 2.1; 95% confidence interval [CI], 0.66-1.54), BF (sHR, 2.14; 0.88-1.83), and cause-specific mortality (sHR, 3.87; 95% CI, 1.31-11). Acute toxicities were higher in group IV versus group I (genitourinary: 38% vs. 26%; P = .01; gastrointestinal: 21% vs. 5%; P = 001). Late toxicities were higher in groups IV and V versus group I (12%-14% vs. 2%-6%; P < .01).

CONCLUSION

Men with T2DM not receiving medication and men with T2DM receiving insulin had worse outcomes and toxicities compared to other patients.

Systematic review and meta-analysis of randomized clinical trials comparing efficacy and safety outcomes of insulin glargine with NPH insulin, premixed insulin preparations or with insulin detemir in type 2 diabetes mellitus

AIMS

A variety of basal insulin preparations are used to treat patients with type 2 diabetes mellitus (T2DM). We aimed to summarize scientific evidence on relative efficacy and safety of insulin glargine (IGlar) and other insulins in T2DM.

METHODS

A systematic review was carried out in major medical databases up to December 2012. Relevant studies compared efficacy and safety of IGlar, added to oral drugs (OAD) or/and in combination with bolus insulin, with protamine insulin (NPH) or premixed insulin (MIX) in the same regimen, as well as with insulin detemir (IDet), in T2DM. Target HbA1c level without hypoglycemic events was considered the primary endpoint.

RESULTS

Twenty eight RCTs involving 12,669 T2DM patients followed for 12-52 weeks were included in quantitative analysis. IGlar + OAD use was associated with higher probability of reaching target HbA1c level without hypoglycemia as compared to NPH + OAD (RR = 1.32 [1.09, 1.59]) or MIX without OAD (RR = 1.61 [1.22, 2.13]) and similar effect as IDet + OAD (RR = 1.07 [0.87, 1.33]) and MIX + OAD (RR = 1.09 [0.86, 1.38]). IGlar + OAD demonstrated significantly lower risk of symptomatic hypoglycemia as compared to NPH + OAD (RR = 0.89 [0.83, 0.96]), MIX + OAD (RR = 0.75 [0.68, 0.83]) and MIX without OAD(RR = 0.75 [0.68, 0.83]), but not with IDet + OAD (RR = 0.99 [0.90, 1.08]). In basal-bolus regimens, IGlar demonstrated similar proportion of T2DM patients achieving target HbA1c as compared to NPH (RR = 1.14 [0.91, 1.44]) but higher than MIX (RR = 1.26 [1.12, 1.42) or IDet (RR = 1.38 [1.11, 1.72]). The risk of severe hypoglycemia was lower in IGlar than in NPH (RR = 0.77 [0.63, 0.94]), with no differences in comparison with MIX (RR = 0.74 [0.46, 1.20]) and IDet (RR = 1.10 [0.54, 2.25]). IGlar + OAD has comparable safety profile to NPH, with less frequent adverse events leading to treatment discontinuation than MIX + OAD (RR = 0.41 [0.22, 0.76]) and IDet + OAD (RR = 0.40 [0.24, 0.69]). Also severe adverse reactions were less common for IGlar + OAD when compared to MIX + OAD (RR = 0.71 [0.52; 0.98]).

CONCLUSION

For the majority of examined efficacy and safety outcomes, IGlar use in T2DM patients was superior or non-inferior to the alternative insulin treatment options.

Pharmacologic Therapy of Diabetes and Overall Cancer Risk and Mortality: A Meta-Analysis of 265 Studies

Different anti-diabetic medications (ADMs) may modify cancer risk and mortality in patients with diabetes. We conducted a systematic review and meta-analysis to estimate the magnitude of association and quality of supporting evidence for each ADM. A total of 265 studies (44 cohort studies, 39 case-control studies, and 182 randomized controlled trials (RCT)) were identified, involving approximately 7.6 million and 137,540 patients with diabetes for observational studies and RCTs, respectively. The risk of bias overall was moderate. Meta-analysis demonstrated that the use of metformin or thiazolidinediones was associated with a lower risk of cancer incidence (RR = 0.86, 95% CI 0.83-0.90, I² = 88.61%; RR = 0.93, 95% CI 0.91-0.96, I² = 0.00% respectively). On the other hand, insulin, sulfonylureas and alpha glucosidase inhibitor use was associated with an increased risk of cancer incidence (RR = 1.21, 95% CI 1.08-1.36, I² = 96.31%; RR = 1.20, 95% CI 1.13-1.27, I² = 95.02%; RR = 1.10, 95% CI 1.05-1.15, I² = 0.00% respectively). Use of other types of ADMs was not significantly associated with cancer risk. This study indicates that some ADMs may modify the risk of cancer in individuals with diabetes. Knowledge of this risk may affect the choice of ADM in individuals concerned about cancer or at increased risk for cancer.

Type 2 diabetes pharmacoepidemiology update 2014: safety versus efficacy

The number of available options for type 2 diabetes has increased steadily over the last decade. These include the insulins, metformin, sulfonylureas, thiazolidinediones, incretin-based therapies, and sodium-glucose cotransporter 2 inhibitors. In this paper, the safety and efficacy of these agents are reviewed with a view on updated findings that have emerged over the last few years. Most drugs for type 2 diabetes effectively lower glycated hemoglobin. Their efficacy is in the range of approximate 0.8-1.5 % reduction in glycated hemoglobin for most agents. No drug for type 2 diabetes has been shown to reduce cardiovascular risk in a clinical trial which represents a gap in the therapeutic armamentarium for type 2 diabetes. Recent evidence has linked the thiazolidinediones to bladder cancer and raised concerns about pancreatic cancer with incretins, which requires further confirmation. The rapidly emerging evidence in the field of pharmacoepidemiology of diabetes will continue to provide answers to important questions on safety and efficacy in 2015 and beyond.