Brazilian cancer biobank targets precision prevention for diverse population

A cancer biobank being assembled at Hospital de Amor in Barretos, São Paulo state, could provide the evidence needed to adapt genetic risk assessment and cancer prevention to Brazil’s diverse population. The initiative has enrolled 4,062 participants and collected nearly 40,000 blood samples, with plans to recruit at least 8,000 people over the next two years, including equal numbers of participants with and without cancer. Researchers are initially studying breast, colorectal and cervical cancers, combining genomic measurements with detailed information on lifestyle, diet, occupation, ancestry and environmental exposures. The project is designed to support risk-prediction tools that could eventually inform more personalized screening within the Unified Health System, or SUS, but the scores are not yet ready for clinical use.

The new biobank is being built on the existing institutional infrastructure of a collection established at Hospital de Amor in 2006. That collection already contains more than 420,000 biological samples from over 55,000 donors, providing the physical and organizational foundation for a focused program in genomic cancer research. The breast, colorectal and cervical cancers selected for the first phase are important health priorities in Brazil and already have established preventive, screening or early-detection measures, including mammography, cervical screening, fecal occult blood testing and colonoscopy. A peer-reviewed paper describing the biorepository and its design was published in iScience, with support from the São Paulo Research Foundation. It documents the infrastructure rather than a completed Brazilian polygenic risk score.

A principal motivation is the limited representation of Brazil’s population in large genomic studies of cancer risk. According to study coordinator Rui Manuel Reis, scientific director of the Hospital de Amor Institute for Teaching and Research, more than 90% of people included in large-scale genomic investigations of cancer risk have European ancestry. Genetic data developed in such populations may transfer poorly to a country whose residents draw on European, African, Indigenous and Asian ancestry, and whose lifestyles and exposures vary substantially across regions. The project’s genetic composition reflects this diversity, and the researchers plan to examine how ancestry is associated with tumor risk and how ancestry affects the performance of risk scores. “We can’t develop precision medicine using a template designed for a European population, with European genetics and a European lifestyle,” Reis said.

One of the main tools the team intends to develop is a polygenic risk score, an approach distinct from testing for a single well-known hereditary mutation. Alterations in genes such as BRCA1 and BRCA2 can confer a substantial increase in the risk of breast and ovarian cancer, but most cancers do not have one genetic alteration that explains an individual’s risk. Instead, many common genetic variants make small contributions, with some slightly raising risk and others slightly lowering it. A polygenic score aggregates information across these variants to estimate a person’s relative genetic predisposition to a particular tumor. The resulting value does not predict whether someone will develop cancer or establish that the disease will occur; it identifies whether that person carries a comparatively higher or lower inherited susceptibility.

Polygenic scores have already been developed through large international genomic studies and are beginning to be used to estimate susceptibility to several diseases, including cancer. Most existing scores, however, were constructed and tested primarily in people of European ancestry. The Hospital de Amor team therefore considers local validation essential before any such score is applied within SUS. Its broader dataset is intended to determine which variants are associated with breast, colorectal and cervical cancer in the Brazilian population, and whether the relationships seen in other populations hold across different ancestry groups. The study also seeks to identify how genetic predisposition interacts with lifestyle and environmental conditions rather than treating genetic information in isolation. Researchers are currently analyzing millions of genetic variations for each participant to determine which are most informative.

That distinction is important because a high polygenic risk score is not equivalent to a diagnosis or a certain future outcome. Cancer can arise through a combination of genetic predisposition and factors such as diet, obesity, physical inactivity, smoking and environmental exposure. To capture those influences, the project pairs blood collection with a comprehensive questionnaire covering participants’ lifestyles, diets, occupations and other potential risk factors. The team also plans to study how genetic variation relates to ancestry and living conditions in Brazil. “We have a very rich biobank of genetic material combined with a very comprehensive epidemiological questionnaire,” Reis said. The researchers hope these data will eventually allow them to develop risk models that reflect Brazilian reality more closely than models based solely on European ancestry.

Potential applications within SUS would involve combining validated genetic findings with other information about risk, rather than using a score alone to determine care. In a hypothetical colorectal cancer pathway, for example, someone found to have a higher genetic predisposition might receive additional attention to modifiable risk factors or, if future studies show a benefit, follow a different screening strategy from someone classified as lower risk, such as referral for an earlier colonoscopy. Similar reasoning could apply to breast and cervical cancer. These possibilities remain contingent: the project has not demonstrated that risk-guided screening improves outcomes, and the source release explicitly notes that the current tool is not ready for implementation in the public health system.

Several stages must precede any clinical rollout. The researchers first need to define which genetic variants and scores are useful, test them in a substantially larger group and validate the results at other centers. If a future test is developed, it is expected to require only a blood sample while examining dozens or hundreds of relevant markers rather than the millions of variations now being analyzed. The investigators also emphasize the need to generate local evidence before introducing tools that were developed abroad. Although genetic risk tests for different conditions are already marketed in Brazil, many were based on overseas research and have not been validated for the Brazilian population. The stated long-term objective is a tool capable of being deployed across SUS, but Reis stressed that validation must come first.

The most advanced results so far concern colorectal cancer and are expected to appear in a separate forthcoming paper; the present publication does not present a ready-to-use Brazilian risk score. The team also plans to expand the biobank to other tumors, including lung cancer, pancreatic cancer and melanoma, and to recruit patients from remote regions who are underrepresented in genomic research. Hospital de Amor’s network will assist with that geographic extension. By consolidating genomic, epidemiological and lifestyle data, the project seeks to ensure that Brazilian populations participate in precision medicine and to build prevention strategies tailored to the country. For now, the biobank’s achievement is the creation of a research platform and an initial cohort, while its proposed value for individualized cancer prevention depends on further model development, validation and evaluation in the public health system.

Subject of Research: Development and validation of a Brazilian biobank for genomic cancer-risk prediction in breast, colorectal and cervical cancers.

Article Title: Brazilian biobank may help personalize cancer prevention in the public health system

Article References: Brazilian biobank may help personalize cancer prevention in the public health system. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: cancer biobank, polygenic risk scores, precision medicine, Brazilian genomics, cancer prevention, breast cancer, colorectal cancer, cervical cancer, genetic ancestry, public health, Brazilian, biobank