For those who are undecided between an endoscopy and a barium swallow test.

The primary purpose of getting a stomach examination during a health checkup is to detect early-stage gastric or esophageal cancer.

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When hearing "gastric endoscopy (stomach camera)," quite a few people likely have a reflexive preconception that it is unpleasant and prefer to avoid it. Additionally, undergoing an endoscopy in the U.S. can involve a considerable cost. However, if you have the option to choose an endoscopy for your health checkup, you should definitely take it. On the other hand, for those planning to undergo a barium swallow test for a health checkup in the U.S., please understand that this test carries the risks and limitations described below.

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Compared to Western countries, Japan has a higher incidence rate of stomach cancer, and barium swallow tests have traditionally been widely adopted as a screening method to detect it early. Countless lives have been saved through a method called the double-contrast technique, which was primarily developed and refined by Japanese physicians and technicians. The historical role that barium tests have played in screening for stomach cancer cannot be denied. Recently, however, their risks and utility are being re-evaluated. One major reason for this is the danger of exposure to large amounts of radiation associated with the procedure. As a result, comprehensive medical check-ups (ningen dock) in Japan are now gradually replacing radiation-heavy barium tests with upper endoscopies, making endoscopies increasingly mainstream.

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So, how much radiation are you actually exposed to during a stomach barium test? It is generally estimated that a direct-imaging barium test exposes an individual to an average of 15 to 25 millisieverts (mSv) of radiation. A sievert is a unit of equivalent dose in living tissue that accounts for the biological effects of different types of radiation. Given that the amount of background radiation naturally received in a year is about 1 to 1.5 mSv, a barium test exposes you to roughly 10 to 25 times that annual amount in a very short period of time.

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Receiving such a large amount of radiation quickly may potentially damage parts of the DNA that make up our genes. Furthermore, continuing to undergo barium tests every year is thought to cause radiation-induced genetic damage to gradually accumulate, and the long-term impact on DNA means the possibility of eventually leading to cancer cannot be ruled out. For reference, the radiation exposure from a direct chest X-ray is 0.07 to 0.1 mSv, meaning a stomach barium test results in an exposure roughly 150 to 350 times greater than a standard chest X-ray. To understand just how massive this exposure is, a radiation exposure chart is helpful: it is astonishingly 2 to 4 times the amount of radiation you would receive by spending one hour at the current Chernobyl nuclear power plant site.

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In 2004, a research group from the University of Oxford published a shocking report in the academic journal The Lancet, estimating that 3.2% of all cancer cases in Japan are caused by radiation exposure from X-ray examinations conducted at medical institutions for health checkups and disease diagnosis (Lancet. 2004 Jan 31;363(9406):345-51). Based on data regarding the frequency of radiological examinations across various countries, radiation doses per examination, and the relationship between radiation exposure and cancer incidence rates by age, sex, and organ, this study estimated the number of cancer cases attributable to radiological exams. The results indicated that in Japan, there are 7,587 such cases annually—staggeringly accounting for 3.2% of all new cancer diagnoses.

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The UK and Poland recorded the lowest rates at 0.6%, while the US stood at 0.9%. Among the 15 countries surveyed, Japan had the highest rate by far. The study revealed that Japan had the highest frequency of radiological exams at 1,477 per 1,000 people annually—1.8 times the 15-country average—resulting in a cancer incidence rate 2.7 times the average. Furthermore, the radiation dose per examination in Japan was higher than in other countries, largely due to the frequent use of high-dose procedures like stomach barium tests and CT scans. Although this report sparked considerable debate regarding its methodology and the interpretation of its results, it served to reaffirm for Japanese medical professionals the ethical importance of avoiding unnecessary X-ray examinations. As a nation that prides itself on being a leader in medical advancement, Japan must reduce excessive X-ray examinations as much as possible in order to overcome the deeply embarrassing reality that 3.2% of all cancers are triggered by diagnostic radiation exposure. There is nothing more absurd than developing stomach cancer from getting a barium swallow test in the name of health.

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Originally, the practice of artificially exposing the body to radiation should only be permitted when the benefits gained clearly outweigh all potential harms, including physical damage from radiation exposure. All medical personnel should pay constant and meticulous attention to keeping radiation exposure for patients to the absolute minimum.

In my personal opinion, unfortunately, the stomach barium tests performed in the United States do not necessarily meet this condition. The incidence rate of stomach cancer in the U.S. is overwhelmingly lower than in Japan, and stomach barium tests (referred to as Upper GI Barium Contrast Studies) are rarely performed here. Consequently, with a few exceptions, the quality of stomach barium exams—which heavily depends on the skill and experience of the physicians and technicians performing and reading them—cannot compare to those done in Japan. I have personally borrowed and reviewed barium test films from several facilities in the U.S., and I was appalled by their poor quality.

The primary purpose of conducting a stomach barium test as part of a health checkup is to detect early-stage stomach or esophageal cancer. The detection rate of early-stage gastric cancer using an upper endoscopy (stomach camera) is incomparably superior to that of a barium test. Even the high-quality barium tests performed in Japan have diagnostic limitations compared to endoscopies. For example, barium tests struggle to detect minute lesions such as early gastric cancers, tend to miss lesions that only present as changes in mucosal color (like gastritis), and frequently miss small esophageal lesions because barium passes through the esophagus too quickly to image well, making flat-type early esophageal cancers difficult to detect. Moreover, if an abnormality is found during a barium test, an endoscopy must be performed anyway.

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On the other hand, an endoscopy allows doctors to directly observe the gastric mucosa, including color changes, take tissue samples from suspicious malignant areas for biopsy and pathological examination, and perform precise observations using special dye staining when necessary. For instance, flat-type cancers, which account for one-third of all early gastric cases, cannot be detected by a barium test alone.

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For the record, the ways in which a stomach barium test is exceptionally superior to an endoscopy are limited to: being able to objectively evaluate the depth of infiltration in advanced cancers, making it easier to diagnose scirrhous gastric cancer (a special type of cancer that spreads along the stomach wall), and—specifically in the U.S.—being less expensive than an endoscopy. An experienced gastroenterologist should be able to thoroughly understand the pros and cons of both barium tests and endoscopies and determine the appropriate examination method based on the situation.

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Many people would prefer to avoid endoscopies because they can be painful and uncomfortable. Admittedly, it cannot be called an easy test, but modern endoscopies use thin, flexible scopes, so the discomfort is generally not as severe as it used to be. Furthermore, an increasing number of facilities are adopting transnasal endoscopy systems, which involve inserting an ultra-thin camera about 5 millimeters in diameter through the nose to minimize patient discomfort.

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In conclusion, regarding stomach examinations for health checkups in the U.S., my opinion is that it is far more meaningful to undergo an endoscopy rather than a barium test. This is driven not only by the passive reason of avoiding cancer risks from heavy radiation exposure, but also by the proactive reason of receiving a higher-quality examination capable of detecting early-stage stomach and esophageal cancers—even after factoring in the higher out-of-pocket cost.