Although many studies have been conducted on the role of alternative medicine in the treatment of cancer, only a few reports have been published regarding the total regression of malignant tumors. At the PBH Research Foundation (PBHRF), two of the authors have used homoeopathic therapy to treat many patients with various malignant tumors. The objective of the present study was to have their treatment procedures evaluated and validated by the United States (US) National Cancer Institute (NCI) Best Case Series (BCS) Program. Lung and oesophageal carcinoma patients were treated with homoeopathic remedies at the PBHRF according to Banerji's protocol until there was complete regression of the tumors. Case records including pathology and radiology reports for 14 patients were submitted for review by the US NCI BCS Program. Four of these cases had an independent confirmation of the diagnosis and radiographic response and were accepted as sufficient information for the NCI to initiate further investigation. These four cases are presented in detail in this report along with follow-up and outcome information. This study describes the process and outcome of a selected case series review through the NCI BCS Program. The results of the review were deemed to be sufficient to warrant NCI-initiated prospective research follow-up in the form of an observational study.