Scientists are exploring an innovative approach to cancer treatment, investigating whether removing specific natural compounds, such as arginine and proline found in common foods like meat and dairy, could hinder the growth of aggressive tumors. This strategy may benefit children with hard-to-treat cancers like neuroblastoma, as well as adults battling mesothelioma, a rare cancer linked to asbestos exposure.

Traditional cancer therapies, including surgery, chemotherapy, radiotherapy, and immunotherapy, have focused on directly attacking tumors. While diet has been mainly viewed as supportive, its potential as a therapeutic tool is gaining attention in the medical community.

A pivotal study published last month in Nature demonstrated that removing arginine and proline from the diet of mice with neuroblastoma reduced tumor aggressiveness. These amino acids, abundant in protein-rich foods such as meat, fish, eggs, and dairy, are converted by tumor cells into polyamines, chemicals essential for their growth.

Researchers at the University Children’s Hospital Zurich, Switzerland, fed the mice a diet lacking arginine and proline. When combined with DFMO, a drug already used to treat neuroblastoma that suppresses polyamine release, the tumors shrank and survival rates doubled. Dr. Raphael Morscher, a pediatric oncologist and study lead, explained: "The combination of the drug and dietary changes boosts the effect of an approved drug."

Experts caution against implementing such restrictive diets for very young children. Instead, researchers aim to replicate the effects via drugs that remove these amino acids from the bloodstream, effectively starving cancer cells. Human trials using this technique are expected to begin next year.

Targeting amino acids has also shown promise in adults. A major international trial published in JAMA Oncology revealed that adding weekly injections of pegargiminase, which depletes arginine from the blood, to chemotherapy extended survival in non-epithelioid mesothelioma patients. By depriving tumors of arginine, cancer cells are weakened, allowing chemotherapy to act more effectively.

Patients on the combination therapy lived an average of 9.3 months, compared to 7.7 months with chemotherapy alone. Three-year survival rates were quadrupled. Professor Peter Szlosarek, lead researcher, noted that cancers lacking the ASS1 gene cannot produce arginine internally, making them dependent on the bloodstream. "Pegargiminase degrades arginine, effectively starving arginine-dependent cancers while sparing healthy cells," he said.

However, diet alone cannot achieve the same effect. Even if arginine intake is eliminated, the body produces it from other amino acids, which would sustain tumor growth. Other amino acids, like methionine and asparagine, have also been studied; restricting them enhanced chemotherapy effectiveness in mice with bowel, breast, and other cancers, with human trials ongoing in the US.

Experts warn that highly restrictive diets can be dangerous. Bernard Corfe, professor of human nutrition at Newcastle University, emphasized that diet alone cannot cure cancer and that reduced protein intake risks muscle loss, tissue damage, and immune compromise. Dr. John Riches from Barts Cancer Institute added that amino acid-deficient diets must be carefully managed to prevent malnutrition, especially in children.

Despite the cautions, Dr. Morscher remains optimistic that targeted dietary interventions could revolutionize cancer treatment. "We are now in an area of precision health," he said. "This study marks a turning point in how we use diet to treat cancer."