Improved Quality of Life After Colon Cancer Surgery Through a Healthy Gut Microbiome

Colon cancer is one of the most common types of cancer in Germany. The most common form is colorectal cancer, which affects the colon and rectum. It usually develops slowly over many years, often from benign colon polyps that can turn into cancer cells. Factors such as diet, lifestyle, and genetic predisposition can increase the risk of developing the disease, but there is no single cause. Treatment usually consists of surgery, often supplemented by chemotherapy or radiation therapy. While these therapies are effective, they can disrupt the balance of the gut microbiota. As a result, many patients continue to suffer from digestive problems such as diarrhea or bloating long after treatment. Previous studies have suggested that so-called symbiotics may reduce the frequency of infections, diarrhea, and inflammation following surgery. Whether synbiotics also improve quality of life or have a positive long-term impact on treatment outcomes has hardly been studied to date. Synbiotics are a combination of live, healthy bacteria (probiotics) and a dietary fiber (prebiotic) that serves as food for these bacteria.

The goal of the LEONORA study is to investigate a symbiotic supplement containing 12 different bacterial strains with regard to its effect on the absence of gastrointestinal symptoms (gastrointestinal quality of life).

To this end, patients are randomly assigned to a treatment group and a control group. The treatment group takes the synbiotic supplement (Essential-Biotic® Complete Delayed-Release Capsules) daily for 12 weeks, starting on days 1–3 after surgery. Starting in the fifth week, the dietary fiber inulin (Orafti® Synergy1 powder)—derived from chicory root and intended to strengthen gut bacteria and restore the microbiome—is gradually added. This prebiotic is dissolved as a powder in a beverage. The control group receives an inactive placebo instead; the protocol is the same as in the treatment group. The study is double-blind, meaning neither the patients nor the treating physicians know which preparation is being administered. The goal is to determine whether the symbiotics improve quality of life with regard to the gastrointestinal tract, for example by reducing diarrhea or bloating. Quality of life is measured using a standardized questionnaire 90 days after surgery. In addition, other health data will be collected, such as blood inflammation markers, infections, cancer recurrence, and overall survival. Stool samples will help determine how the therapy affects the composition of the gut microbiota.

Eligible participants are adults aged 18 and older with confirmed colorectal cancer who will undergo surgery within 14 days at one of the eleven study centers in Germany. Patients must be willing to provide blood and stool samples or a rectal swab before and after surgery. Excluded from participation are, among others, pregnant women, insulin-dependent diabetics, people with severe cognitive impairments, individuals taking immunosuppressive medications, and participants in other nutrition-related studies.