Eighty years have passed since the atomic bomb. Solid cancer is the most important late radiation effect, and its epidemiological characteristics include a long-term increase in incidence over several decades after exposure, but the molecular mechanism underlying this has yet to be elucidated. We recently found that young people exposed to radiation at close range had an increased incidence of multiple cancers. Even now, 80% of the young atomic bomb survivors under the age of 10 are still alive, and as the survivors age, the number of cancer cases is expected to continue to increase. Tissue samples from atomic bomb survivors are valuable and essential for detailed analysis of the molecular mechanisms of long-lasting radiation effects on the human body. Until now, research has mainly focused on tissue samples preserved as formalin-fixed paraffin blocks prepared for pathological diagnosis, but there are limitations to comprehensive analysis due to the fragmentation of nucleic acids.

As part of the Atomic Bomb Medical Research Project of the Nagasaki University Global COE Program "Global Strategic Center for Radiation Health Risk Control", which was adopted in fiscal year 2007, we began collecting fresh-frozen tumor tissue samples from Nagasaki atomic bomb survivors in April 2008. The collection process is as follows. This research plan was approved by the Ethics Committee of The Japanese Red Cross Nagasaki Genbaku Hospital and the Ethics Review Committee of Nagasaki University Hospital. The target is people with an atomic bomb survivor's certificate who will undergo tumor resection surgery at the Nagasaki University Hospital Surgery Department or The Japanese Red Cross Nagasaki Genbaku Hospital Surgery Department. First, information about the circumstances of the exposure, the plan for the donation of the excised tissue and genetic analysis are explained in writing, and consent is obtained. Once consent is obtained, information about the radiation exposure situation, family history, medical history, etc. will be collected and compiled into a database. The tumor and surrounding normal tissue are removed during surgery and then frozen and preserved. The frozen samples obtained, along with radiation exposure and other medical information, will be anonymized and stored at the Atomic Bomb Disease Institute. By the end of March 2025, fresh-frozen tumor tissues from 898 cases (839 people) had been collected. Of these, 102 cases (12.16%) were close-range exposures less than 2 km from the hypocenter, which are thought to have a relatively strong radiation effect. The most common cancer sites are: lung (221 cases), breast (170 cases), colon (132 cases), stomach (104 cases), liver (87 cases), and thyroid (66 cases). However, we reported on the current status of the Nagasaki Atomic Bomb Survivors Tumor Tissue Bank, stating that the number of collected samples has decreased significantly due to the recent COVID-19 pandemic, and that the banking of valuable tumors from proximal survivors is in jeopardy.

It is believed that some factor induced by atomic bomb radiation is involved in the increased cancer risk among atomic bomb survivors. Once the samples are accumulated and the Nagasaki Atomic Bomb Survivors Tumor Tissue Bank is established, more detailed analyses, such as comprehensive genetic analysis and genetic polymorphism analysis, will become possible, so we will continue to collect samples. Currently, we are working with other research institutions to conduct whole genome analysis using samples from the Nagasaki Atomic Bomb Survivors Tumor Tissue Bank.