Ramón Salazar

In 2024, some 2.3 million new cases of cancer worldwide were linked to infections — 12 per cent of all cases diagnosed that year — according to a study published in the journal The Lancet Oncology. Almost all of these cases are linked to five pathogens: the stomach bacterium Helicobacter pylori, the human papillomavirus (HPV), the hepatitis B and C viruses, and the Epstein-Barr virus. Low- and middle-income countries account for 77 per cent of all infection-related cancer cases.

Infection with the bacterium Helicobacter pylori is a known risk factor for stomach cancer. Its link to colorectal cancer, however, remains an unconfirmed hypothesis. An international team has reviewed 43 studies on this subject and found that 22 per cent of colorectal cancer cases could potentially be linked to this infection, although when they selected the 14 most reliable studies, the figure fell to 12 per cent. According to the authors, exposure to Helicobacter pylori could be contributing significantly to the number of cases of colon cancer worldwide, but they point out that their study is only exploratory and that more robust research, such as clinical trials, is needed to establish a causal link. The results have been published in eGastroenterology.

A team of researchers in South Korea has analysed the oral and faecal microbiomes of just over 507 volunteers and has concluded that, in patients with gastric and colorectal cancer, there is a greater transfer of microbes from the mouth to the gut. Furthermore, not only does this transfer differ between tumour types, but, according to their findings, an analysis based on oral samples is capable of detecting colorectal cancer with greater sensitivity than the standard faecal occult blood test. However, “before it can be used in practice, clinical trials would need to be carried out in real-world screening populations”, the authors explain. The study is published in the journal Cell Host & Microbe.

[Nature Medicine has retracted this article on 24 June 2026]

A phase 3 clinical trial conducted in China tested 210 patients with advanced non-small cell lung cancer—the most common type—to see whether the time of day when immunotherapy and chemotherapy were administered influenced their effectiveness. The data indicate that, on average, those who received therapy after 3 p.m. did not see their cancer worsen for 5.4 months. In contrast, those who received it before that time did not see their cancer worsen for an average of 11.7 months, almost twice as long. Overall, response rates were 56.2% and 69.5%, respectively. The results, published in Nature Medicine, suggest that scheduling therapy early in the day may offer a simple and cost-free way to improve treatment efficacy.

The use of hormonal contraceptives is associated with a small increase in the risk of breast cancer—one additional case of cancer for every 7,752 women who use these drugs—according to a Swedish study. The risk varies depending on the type of hormones administered, and is slightly higher with the use of contraceptives containing desogestrel. The study, published in JAMA Oncology, analyses data from a national registry between 2006 and 2019, with more than two million women aged between 13 and 49.

For women diagnosed with early-stage breast cancer, the long-term risk of developing a second primary cancer is low, around 2–3 per cent higher than that of women in the general population. This is one of the conclusions of a study published by The BMJ, which analysed data from nearly half a million women diagnosed in England between 1993 and 2016 with early-stage invasive breast cancer who underwent surgery. During a follow-up period of up to 20 years, around 65,000 women developed a second primary cancer, but the absolute excess risk compared to the risks in the general population was small.

A team led by the Spanish National Cancer Research Centre (CNIO) has shown in mice that a high-fat diet increases metastasis in triple-negative breast cancer, which has the worst prognosis. In addition, it has identified several of the mechanisms that would explain this, such as the activation of platelets and coagulation, which would help the tumour hide from the body's defences and prepare the so-called ‘pre-metastatic niche’. According to the researchers, who published the results in Nature Communications, ‘this mechanism could be extrapolated to other tumour types and other organs’. The results suggest that ‘dietary intervention, together with the control of platelet activity, may increase the efficiency of certain anti-tumour treatments’.

An international team has found that aspirin is capable of reducing the appearance of metastasis in mice, by enabling the activation of T lymphocytes capable of recognising tumour cells. The research showed that several different mouse cancer models — including breast cancer, colon cancer and melanoma — treated with aspirin showed a lower rate of metastasis in other organs, such as the lungs and liver, compared to untreated mice. According to the authors, who publish the results in the journal Nature, ‘the finding paves the way for the use of more effective anti-metastatic immunotherapies’.

Research led by the Hospital del Mar Research Institute (Barcelona) and involving researchers from CIMA (University of Navarra) and Pompeu Fabra University (Barcelona) has revealed the existence of microproteins present almost exclusively in hepatocellular carcinoma, the most common form of liver cancer. These structures, which appear to be found in a significant percentage of patients, could be used to develop specific vaccines against this type of tumour. The results are published in the journal Science Advances.

The classical view describes most cancers as the result of mutations that happen by chance and accumulate over a lifetime. Now, a study claims to break that paradigm. A team of researchers from Stanford University (USA) has described that the genetics we inherit influences the surveillance that our defences do of these mutations, conditioning the type of tumour that can develop and its prognosis. The results, which for the moment refer to breast cancer, are published in the journal Science.