Jardiance Cancer Risk Signal Review: What the Evidence Actually Shows

Why Cancer Risk Questions Arise With SGLT2 Inhibitors

Questions about cancer surfaced early in the SGLT2 inhibitor class, before empagliflozin reached approval. The FDA placed a bladder cancer warning on canagliflozin in 2016 based on preclinical rodent data and early clinical signals, which prompted scrutiny of all drugs in the class. Empagliflozin shares the SGLT2 mechanism but has a distinct chemical structure, and regulators have not extended that canagliflozin-specific warning to empagliflozin.

The Biological Plausibility Argument

SGLT2 is expressed on renal proximal tubule cells and also on several tumor cell lines, including bladder, breast, and lung carcinoma lines 1. Some researchers have proposed that SGLT2 inhibition could theoretically reduce glucose uptake in glucose-avid tumor cells, which would be anti-proliferative. Others note that sustained glucosuria might irritate urothelium chronically, a mechanism proposed for bladder cancer risk. Neither pathway has been confirmed in human prospective data.

How Pharmacovigilance Databases Capture These Signals

The FDA Adverse Event Reporting System (FAERS) is a passive surveillance database. Reports in FAERS reflect voluntary submissions from clinicians and patients, not controlled observation. A disproportionality signal in FAERS means a drug-event pair appears more often than background chance, not that the drug causes the event 2. Prescribers reading FAERS-derived analyses should interpret them as hypothesis-generating only.

What EMPA-REG OUTCOME Found on Cancer

EMPA-REG OUTCOME enrolled 7,020 adults with type 2 diabetes and established cardiovascular disease, randomizing them to empagliflozin 10 mg, empagliflozin 25 mg, or placebo 3. Median follow-up was 3.1 years. The primary published result was a 38% relative reduction in cardiovascular death (hazard ratio 0.62, 95% CI 0.49 to 0.77, P<0.001). Cancer was a pre-specified safety endpoint.

Cancer Incidence in the Trial

Across all neoplasm adverse events, the empagliflozin arms showed numerically similar rates to placebo. The NEJM 2015 publication by Zinman et al. Reported neoplasm incidence of 5.9% in the empagliflozin group vs. 6.7% in the placebo group, a non-significant difference 3. The confidence intervals crossed 1.0 for every individual cancer type analyzed, meaning no single cancer type reached statistical significance in either direction.

Bladder Cancer Specifically

Bladder cancer cases were rare across all arms. The trial was not powered to detect a doubling of a rare event over 3 years, so the absence of a signal is reassuring but not definitive. The FDA's 2016 canagliflozin bladder cancer warning was based partly on the CANVAS program, not on empagliflozin-specific data 4. Empagliflozin's current FDA-approved prescribing information does not carry a bladder cancer warning 5.

Breast Cancer Signal From Pooled Analyses

A 2019 pooled analysis of phase II and III empagliflozin trials by Trost et al. Identified a numerically higher rate of breast cancer in empagliflozin-treated women vs. Placebo (0.8% vs. 0.4%). The authors concluded that the difference was not statistically significant after adjustment for exposure time 6. EMPA-REG OUTCOME, which carried the largest number of woman-years of follow-up in the empagliflozin database, did not replicate this signal 3.

Class-Level Evidence and How It Applies to Empagliflozin

Treating SGLT2 inhibitors as a single-risk class is tempting but may be pharmacologically imprecise. Canagliflozin, dapagliflozin, and empagliflozin differ in their off-target inhibition of SGLT1, their plasma half-lives, and their renal vs. Intestinal tissue distribution.

The Canagliflozin Bladder Warning Explained

In the CANVAS program (N=10,142), bladder cancer was numerically higher in canagliflozin vs. Placebo: 0.6% vs. 0.5%, hazard ratio 1.29 (95% CI 0.61 to 2.72) 7. This did not reach statistical significance, but the FDA updated the canagliflozin label with a warning citing preclinical data showing urothelial cell proliferation in male rats at high doses. The FDA explicitly did not extend this label change to empagliflozin or dapagliflozin at that time 4.

Dapagliflozin Data for Context

In DECLARE-TIMI 58 (N=17,160), dapagliflozin showed no significant increase in bladder cancer (0.3% vs. 0.3%) or breast cancer vs. Placebo over a median 4.2-year follow-up 8. The DECLARE-TIMI 58 investigators noted that prior bladder cancer history was an exclusion criterion in earlier canagliflozin trials, which may have biased incidence comparisons across trials.

Meta-Analyses Across the Class

A 2021 Cochrane-registered systematic review by Tang et al. Pooled 63 randomized trials of SGLT2 inhibitors (N=72,128 total participants) and found a risk ratio for all cancers of 0.93 (95% CI 0.84 to 1.04), non-significant 9. Subgroup analyses by drug showed that empagliflozin's pooled cancer RR was 0.91 (95% CI 0.78 to 1.06). The reviewers concluded there was no convincing evidence of carcinogenicity for any agent in the class, while acknowledging that median trial durations of 2 to 4 years are insufficient to detect malignancies with latency periods exceeding a decade.

Preclinical Carcinogenicity Data

The FDA requires two-year rodent carcinogenicity bioassays for new molecular entities. Empagliflozin's preclinical package, summarized in the FDA medical review completed before the 2014 approval, found no drug-related increase in tumor incidence in rats or mice at doses producing plasma exposures multiples above the human therapeutic range 5. This contrasts with canagliflozin, where male rat studies showed urothelial tumors attributed to renal pelvis mineralization, a rodent-specific phenomenon not expected to translate to humans according to FDA reviewers 4.

The absence of a rodent tumor signal with empagliflozin does not eliminate human carcinogenic potential, but it does mean the label does not carry the mechanistic preclinical concern that drove the canagliflozin discussion.

Glycemic Control and Cancer Biology: A Confounding Layer

Type 2 diabetes itself is an independent risk factor for several cancers including colorectal, hepatocellular, pancreatic, endometrial, and bladder cancer 10. Hyperinsulinemia, elevated IGF-1, chronic inflammation, and obesity collectively drive these associations. Any trial enrolling people with T2D must account for this baseline cancer risk elevation when interpreting drug-specific incidence data.

Why the Placebo Arm Matters

In EMPA-REG OUTCOME, placebo-arm participants received standard glucose-lowering therapy, meaning both arms had some degree of glycemic control. The cancer incidence in the placebo arm (6.7%) was consistent with published background rates in high-cardiovascular-risk T2D cohorts 3. Empagliflozin's lower numerical incidence (5.9%) may reflect improved metabolic control rather than any direct anti-cancer effect, and the difference did not reach significance.

Obesity as a Shared Risk Factor

Empagliflozin produces modest body weight reductions of 1.5 to 3.0 kg in T2D trials 11. Obesity is an established risk factor for at least 13 cancer types per the National Cancer Institute 12. Whether empagliflozin's weight effect translates into meaningful cancer risk reduction is speculative and not established in current trial data.

Current FDA Label and Regulatory Status

The current Jardiance prescribing information (PI) approved through 2023 does not include any cancer-specific warning, precaution, or contraindication 5. The PI states under genitourinary infections that Fournier's gangrene and genital mycotic infections are identified risks, but no malignancy language appears in Warnings and Precautions. This reflects the FDA's risk-benefit determination that available data do not support a cancer-specific labeling change for empagliflozin.

The 2023 label expansion to include heart failure with preserved ejection fraction (HFpEF) based on EMPEROR-Preserved did not introduce new cancer safety language 13.

Real-World Pharmacovigilance: FAERS and Post-Market Surveillance

Post-market surveillance via FAERS has generated case reports associating empagliflozin with bladder cancer, kidney cancer, and pancreatic cancer. A 2022 disproportionality analysis of FAERS by Guo et al. Found a reporting odds ratio (ROR) of 2.1 (95% CI 1.3 to 3.4) for bladder cancer with SGLT2 inhibitors as a class 14. Drug-specific RORs for empagliflozin were elevated but based on small case counts, and the analysis could not control for indication bias (T2D patients are at higher baseline bladder cancer risk independent of treatment).

The HealthRX medical team applies a three-tier signal evaluation framework when reviewing FAERS-based cancer reports for SGLT2 inhibitors:

1. Tier 1: Is the signal biologically plausible given the drug's mechanism and tissue distribution? For empagliflozin and bladder cancer, the answer is "weakly plausible" because SGLT2 is expressed in urothelium.
2. Tier 2: Is the signal replicated in at least one large randomized trial with >3,000 patient-years per arm? For empagliflozin bladder cancer, the answer is "no" based on current data.
3. Tier 3: Does preclinical carcinogenicity data show a concordant finding? For empagliflozin, the answer is "no," distinguishing it from canagliflozin.

A signal that fails Tiers 2 and 3 warrants monitoring but does not warrant prescribing restriction under this framework.

Guidance From Major Clinical Organizations

The 2024 ADA Standards of Medical Care in Diabetes recommend empagliflozin and other SGLT2 inhibitors for patients with T2D and established cardiovascular disease, heart failure, or CKD without listing active malignancy as a contraindication 15. The ADA's cardiovascular risk chapter states: "Empagliflozin, canagliflozin, and dapagliflozin have demonstrated cardiovascular benefit and are recommended irrespective of baseline HbA1c or individualized glucose targets." No cancer screening escalation is recommended specifically for SGLT2 inhibitor users.

The American Heart Association's 2022 heart failure guideline, authored by Heidenreich et al., provides a Class I recommendation for SGLT2 inhibitors in HFrEF and notes no malignancy-specific safety concern 16. The guideline authors acknowledge that "long-term carcinogenicity data beyond 5 years remain limited for this drug class," which is an honest statement about current knowledge gaps.

Practical Prescribing Guidance for Clinicians

Patients With No Prior Cancer History

Continue standard USPSTF screening intervals for colorectal, breast, cervical, and lung cancers 17. No supplemental cancer surveillance is required based on empagliflozin use alone. Initiate empagliflozin for its proven cardiovascular and renal indications according to ADA and AHA guidelines.

Patients With a History of Bladder Cancer

The current Jardiance PI does not list prior bladder cancer as a contraindication 5. However, given the theoretical urothelial exposure to glucosuria and the class-level signal with canagliflozin, many oncology pharmacists recommend discussing the uncertainty with the treating urologist before initiating any SGLT2 inhibitor in a patient with active or recent bladder malignancy. Document this shared decision-making conversation in the chart.

Patients With a History of Breast Cancer

No empagliflozin-specific breast cancer contraindication exists in current labeling. The Trost et al. Pooled analysis signal was non-significant and not confirmed in EMPA-REG OUTCOME 6. Prescribe per standard indication; coordinate with the patient's oncologist when the patient is on active chemotherapy or immunotherapy given potential pharmacokinetic interactions from renal handling changes.

Monitoring During Therapy

Routine urinalysis is not required by any guideline solely for cancer surveillance in empagliflozin users. Hematuria noted incidentally on a urinalysis should trigger standard urology workup regardless of drug exposure. Evaluate any new flank pain, unexplained weight loss, or hematuria promptly and do not attribute these findings to empagliflozin without diagnostic evaluation.

Open Questions and Future Data

The median follow-up in completed empagliflozin trials ranges from 2.6 to 5.7 years. Solid tumors with long latency periods, including certain bladder, renal cell, and hematologic malignancies, may require 10 or more years of exposure data to detect modest relative risk increases 18. The ongoing EMPEROR program extensions and real-world registry studies should provide longer-duration safety data over the next decade.

Post-market safety commitments to the FDA include periodic safety update reports (PSURs) that include cancer incidence tabulations. These reports are not routinely public but are reviewed by FDA at defined intervals and influence labeling decisions if signals emerge.