Antibiotics may prevent bacteria-mediated chemoresistance in patients with metastatic pancreatic cancer, according to research published in JAMA Network Open.

The study showed that patients treated with gemcitabine had an improvement in overall survival (OS) and cancer-specific survival (CSS) if they received antibiotics. 

This retrospective study included 3850 patients with unresectable, metastatic pancreatic ductal adenocarcinoma. They were treated with first-line gemcitabine (81.8%) or fluorouracil (18.2%) from 2007 through 2017. 

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The researchers matched 1672 patients who received antibiotics with 1672 patients who did not. Antibiotics were given in the month before or after starting chemotherapy. Patients either received 1 antibiotic injection or they took oral antibiotics for at least 5 days. 

There was a significant improvement in OS and CSS with antibiotics both in the overall matched cohort and among patients who received gemcitabine. Patients treated with fluorouracil, on the other hand, did not derive any benefit from antibiotics.

In the overall cohort, the median OS was 7.3 months among patients who received antibiotics and 6.8 months among those who did not (hazard ratio [HR], 0.93; 95% CI, 0.86-0.99; P =.03). In addition, there was an 11% improvement in CSS among patients who received antibiotics (HR, 0.89; 95% CI, 0.82-0.96; P =.004).

In the gemcitabine-treated group, the median OS was 7.1 months for patients who received antibiotics and 6.5 months for those who did not (HR, 0.89; 95% CI, 0.83-0.96; P =.003). There was a 16% improvement in CSS among patients who received antibiotics in this group (HR, 0.84; 95% CI, 0.77-0.92; P <.001).

In the fluorouracil-treated group, the median OS was 8.6 months for patients who received antibiotics and 9.2 months for those who did not (HR, 1.08; 95% CI, 0.90-1.29; P =.41). There was no significant difference in CSS between patients who received antibiotics and those who did not (HR, 1.12; 95% CI, 0.90-1.36; P =.29).

The researchers also evaluated the role of antibiotic class and route of administration. They found that non-penicillin β-lactams were associated with an 11% reduction in the risk of death (HR, 0.89; 95% CI, 0.81-0.97; P =.01) when compared with all other antibiotic classes. In addition, there was a trend toward a lower risk of death with injectable antibiotics compared with oral antibiotics (HR, 0.91; 95% CI, 0.82-1.00; P =.05). 

These results suggest that “antibiotics may modulate bacteria-mediated gemcitabine resistance and have the potential to improve PDAC [pancreatic ductal adenocarcinoma] outcomes,” the researchers concluded.

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Fulop DJ, Zylberberg HM, Wu YL et al. Association of antibiotic receipt with survival among patients with metastatic pancreatic ductal adenocarcinoma receiving chemotherapy. JAMA Netw Open. Published online March 23, 2023. doi:10.1001/jamanetworkopen.2023.4254