Impact of Deuterium-Depleted Water on Long-Term Tumor Survival Demonstrated in a Case of Prostate and Breast Cancer

Background: Long-term survival remains, as a less studied aspect, a major challenge in oncology because the efficacy of treatments is often determined based on short-term results. Deuterium-depleted water (DDW) has emerged as a potential adjunctive treatment with reported benefits in several cancer types. Cases: This study presents two long-term analysis of two cases—a prostate cancer patient who relapsed after prostatectomy and a breast cancer patient diagnosed in stage IV. Both patients consumed DDW intermittently in addition to standard therapies. Clinical parameters, including prostate-specific antigen (PSA) and Ca 15-3 tumor marker were followed for 21 and 18 years, respectively, to assess the potential association between DDW consumption and disease stability. Results: In both patients, continuous or repeated consumption of DDW was associated with sustained remission and stable disease markers. After discontinuation of DDW consumption, increases in PSA or Ca 15-3 levels were observed, while reintroduction of DDW was associated with decreases in markers and stabilization of clinical status. These observations are consistent with previous studies in larger patient groups, where continuous DDW consumption during remission was associated with significantly prolonged median survival times. Conclusion: Based on the presented long-term observations, DDW may contribute to the maintenance of remission and delay cancer progression when used as part of standard treatments. Due to its favorable safety profile, DDW may be used as a potential adjunctive therapy in long-term oncology care. Controlled clinical trials are needed to confirm these observations and to develop standardized protocols for DDW treatment in different tumor types.