From Geriatric Pharmacy intern Jessica Enogieru PharmD(c) University of Florida College of Pharmacy
Several studies looking at the association between insulin glargine (Lantus) and cancer risk have shown conflicting results. One study (Hemkens) compared the mitogenic (growth promoting) potencies of several insulin analogues (lispro, aspart, glargine) and human insulin. After adjusting for insulin dose, the study showed a significant, dose dependent increase in the risk of cancer in patients treated with insulin glargine versus human insulin. A second study showed an increasing cancer risk with only one type of cancer (breast cancer). The third study did not find a significant association between insulin glargine and cancer risk, but analysis performed in a subset of patients who received insulin glargine exclusively revealed an increase risk of all cancers and breast cancer. A fourth study found no association between increased cancer risk and insulin glargine. On the surface, these findings seem very alarming. But worried diabetic patients using insulin analogues like glargine should consider these three points.
First the study results are conflicting. In the study done by Hemkens et al in Germany, the unadjusted analysis showed a lower cancer incidence in glargine-treated patients while the adjusted data showed a dose dependent increase in cancer risk with glargine. Another study of 114,841 Swedish diabetic patients suggested an increased risk of breast cancer during exclusive treatment with insulin monotherapy. After adjustment for age and sex, use of insulin glargine doubled the risk of breast cancer. In contrast, a Scottish study of 50,000 patients treated with insulin found no increased cancer risk associated with use of insulin glargine. Overall, patients using insulin glargine had the same incidence of cancers as patients who did not receive glargine. Using 62,809 diabetic patients, British investigators found an increased risk of solid tumors in patients treated with insulin or insulin secretagogues compared with metformin. However, the addition of metformin to insulin eliminated most of the excess risk and analysis of cancer risk by type of insulin used showed no difference in patients treated with human insulin or insulin analogs.
Second all of the studies done were epidemiological studies; they retrospectively looked at large databases to find associations between types of cancer and types of insulin. However that type of study is much less robust than a randomized controlled trial (RCT), which is considered the gold standard. Epidemiological studies come with a lot of pitfalls and their results should be evaluated carefully.
Third experts in diabetes care believe the results are not strong enough to sanction a change in insulin treatment for diabetes. The American Diabetes Association, American Association for Clinical Endocrinologists, and European Association for the Study of Diabetes issued statements saying the evidence was insufficient to warrant changes in a diabetic patient's current insulin regimen. Furthermore, the authors of the studies agreed that their findings did not warrant changes to diabetic insulin regimens.
In essence, the moral of the story is that diabetics should continue to use insulin glargine and other insulin analogues. Until a substantial casual relationship between insulin glargine and cancer risk is found, the benefits of treatment outweigh the risks.
Several studies looking at the association between insulin glargine (Lantus) and cancer risk have shown conflicting results. One study (Hemkens) compared the mitogenic (growth promoting) potencies of several insulin analogues (lispro, aspart, glargine) and human insulin. After adjusting for insulin dose, the study showed a significant, dose dependent increase in the risk of cancer in patients treated with insulin glargine versus human insulin. A second study showed an increasing cancer risk with only one type of cancer (breast cancer). The third study did not find a significant association between insulin glargine and cancer risk, but analysis performed in a subset of patients who received insulin glargine exclusively revealed an increase risk of all cancers and breast cancer. A fourth study found no association between increased cancer risk and insulin glargine. On the surface, these findings seem very alarming. But worried diabetic patients using insulin analogues like glargine should consider these three points.
First the study results are conflicting. In the study done by Hemkens et al in Germany, the unadjusted analysis showed a lower cancer incidence in glargine-treated patients while the adjusted data showed a dose dependent increase in cancer risk with glargine. Another study of 114,841 Swedish diabetic patients suggested an increased risk of breast cancer during exclusive treatment with insulin monotherapy. After adjustment for age and sex, use of insulin glargine doubled the risk of breast cancer. In contrast, a Scottish study of 50,000 patients treated with insulin found no increased cancer risk associated with use of insulin glargine. Overall, patients using insulin glargine had the same incidence of cancers as patients who did not receive glargine. Using 62,809 diabetic patients, British investigators found an increased risk of solid tumors in patients treated with insulin or insulin secretagogues compared with metformin. However, the addition of metformin to insulin eliminated most of the excess risk and analysis of cancer risk by type of insulin used showed no difference in patients treated with human insulin or insulin analogs.
Second all of the studies done were epidemiological studies; they retrospectively looked at large databases to find associations between types of cancer and types of insulin. However that type of study is much less robust than a randomized controlled trial (RCT), which is considered the gold standard. Epidemiological studies come with a lot of pitfalls and their results should be evaluated carefully.
Third experts in diabetes care believe the results are not strong enough to sanction a change in insulin treatment for diabetes. The American Diabetes Association, American Association for Clinical Endocrinologists, and European Association for the Study of Diabetes issued statements saying the evidence was insufficient to warrant changes in a diabetic patient's current insulin regimen. Furthermore, the authors of the studies agreed that their findings did not warrant changes to diabetic insulin regimens.
In essence, the moral of the story is that diabetics should continue to use insulin glargine and other insulin analogues. Until a substantial casual relationship between insulin glargine and cancer risk is found, the benefits of treatment outweigh the risks.