---
title: "Cancer incidence trends in the Ecuadorian Amazon, 1990–2019: a registry-based analysis"
id: "plos-one-19-cancer-incidence-in-the-ecuadorian-amazon-a-retrospective-study-1990-2019"
canonical_url: "https://medichelpline.com/clinical-feed/plos-one-19-cancer-incidence-in-the-ecuadorian-amazon-a-retrospective-study-1990-2019"
content_type: "clinical_feed_article"
specialty: "Oncology"
source_name: "PLOS ONE (Medicine)"
source_url: "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0359707"
published_at: "2026-10-05T14:00:00.000Z"
evidence_level: "Journal Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Cancer incidence trends in the Ecuadorian Amazon, 1990–2019: a registry-based analysis
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/plos-one-19-cancer-incidence-in-the-ecuadorian-amazon-a-retrospective-study-1990-2019
- **Specialty:** [Oncology](https://medichelpline.com/clinical-feed/oncology.md)
- **Primary Source:** PLOS ONE (Medicine)
- **Source URL:** [Original Journal Publication](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0359707)
- **Published At:** 2026-10-05T14:00:00.000Z
- **Evidence Rating:** Journal Feed
## Executive GIST (TL;DR)
- This retrospective, registry-based ecological study analysed cancer incidence among residents of four Ecuadorian Amazon provinces (Sucumbíos, Orellana, Napo, Pastaza) using the **Quito Population-Based Cancer Registry** for 1990–2019. - A total of 5,008 cases were recorded; 4,881 cases were included in analyses after excluding 127 with missing age or province. 36.8% of analyzed cases were men. - The number of recorded cancer cases increased by 357% between 1990–1994 and 2015–2019, with increases observed in both sexes. - Age-standardised incidence rates rose substantially: in men from 19 to 50 per 100,000 (a 163.2% increase) and in women from 37 to 96 per 100,000 (a 159.5% increase). - Most frequent cancers in men across the study were **prostate cancer**, stomach, non-melanoma skin, and lymphoid leukemia; prostate increased over time while stomach declined. - In women the leading cancers were **cervical cancer** (invasive and in situ), **breast cancer**, thyroid, and non-melanoma skin; cervical cancer decreased while breast and thyroid increased. - In 2015–2019 the five most frequent cancers per 100,000 were: men — prostate (8.3), stomach (5.4), non-melanoma skin (4.9); women — invasive cervical (18.2), breast (13.6), thyroid (11.8). - Quasi-Poisson regression adjusted for age and sex estimated a 22.8% increase in overall cancer incidence per 5-year period (IRR 1.23, 95% CI 1.20–1.25). Incidence increased faster in women (≈24.7% per period) than men (≈19.7% per period). - The study highlights potential contributors to rising recorded incidence: demographic ageing, improved case ascertainment and access to diagnostic services, and possible true increases in disease burden. - The Amazon provinces lack provincial histopathology and oncology services and have no organised regional cancer prevention programmes, which likely affect case capture and access to care. - Authors call for strengthened healthcare infrastructure, improved cancer registry coverage, and targeted prevention and early detection programmes adapted to the region’s needs.
## Clinical Analysis & Structured Key Points
Cancer incidence in the Ecuadorian Amazon: A retrospective study (1990–2019) | PLOS One Browse Subject Areas ? Click through the PLOS taxonomy to find articles in your field. For more information about PLOS Subject Areas, click here . Article Authors Metrics Comments Media Coverage Reader Comments Figures Figures Abstract Background There is a scarcity of cancer studies in the Amazon region. This study aimed to analyse trends in cancer incidence within the Ecuadorian Amazon between 1990 and 2019, identifying the most prevalent cancer types and assessing their provincial and temporal distribution. Methods A retrospective analysis was conducted using data from the Quito population-based cancer registry, focusing on patients whose habitual residence was in the Amazonian provinces of Sucumbíos, Orellana, Napo, and Pastaza. Age- and sex-standardised incidence rates were calculated, employing Segi’s world standard population as the reference. Results A total of 4,881 cancer cases were identified, revealing a 357% increase in the number of recorded cancer cases from the first to the last study period. Among men, the most common cancer types were stomach, prostate, and non-melanoma skin cancers, whereas in women, cervical, breast, and thyroid cancers predominated. Notably, there was a particularly high increase in prostate and breast cancer cases. Conclusions The findings indicate an important increase in recorded cancer cases and age-standardized incidence rates in the Ecuadorian Amazon, highlighting the urgent need to enhance healthcare infrastructure and cancer registry systems in the region. Targeted prevention and early detection programmes tailored to the specific needs of this population are urgently needed. Citation: San Sebastián M, Fonseca-Rodriguez O, Tarupi W, Castel-Feced S (2026) Cancer incidence in the Ecuadorian Amazon: A retrospective study (1990–2019). PLoS One 21(10): e0359707. https://doi.org/10.1371/journal.pone.0359707 Editor: António Machado, Universidade dos Açores Departamento de Biologia: Universidade dos Acores Departamento de Biologia, PORTUGAL Received: January 3, 2026; Accepted: September 17, 2026; Published: October 5, 2026 Copyright: © 2026 San Sebastián et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: The data underlying the results presented in the study are available from the National Cancer Registry from Ecuador https://solcaquito.org.ec/registro-nacional-de-tumores/ . Funding: The author(s) received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist. Introduction Cancer remains a leading cause of mortality globally, accounting for nearly 10 million deaths in 2022. The cancers with the highest incidence worldwide include breast, lung, colorectal, and prostate cancers [ 1 ]. Effective prevention and control of these diseases necessitate robust information systems. Population-based cancer registries play a pivotal role as continuous surveillance mechanisms, systematically collecting data on new cancer cases within defined populations. These registries are essential for calculating incidence and mortality rates and serve as reliable sources for health policy planning and impact assessment [ 2 ]. The Amazon region, one of the most biodiverse and expansive areas globally, spans approximately 7.5 million square kilometers across nine countries and harbors about 10% of all known species. It is home to numerous Indigenous communities and rural populations with historical migration patterns. The Amazon basin has a very low population density overall, with fewer than six people per square kilometre on average (around 3–4 in Brazil’s part). This is due to challenging rainforest conditions, difficult terrain and poor agricultural soil, with most people concentrated in urban centres [ 3 ]. However, the Amazon faces multiple challenges, including deforestation, illegal mining, wildlife trafficking, and climate change, which threaten both its biodiversity and the well-being of its inhabitants. In this complex context, cancer in the Amazon region represents a multifaceted challenge, intertwining environmental, socioeconomic, healthcare access, and case registration factors. Understanding these interactions is crucial for effectively addressing this public health issue [ 4 , 5 ]. Evidence on cancer in the Amazon region remains scarce. A recent study among Indigenous populations in the Brazilian Amazon found that cervical, stomach, and liver cancers accounted for 52% of cases between 2000 and 2012, with higher incidence rates compared to non-Indigenous counterparts. The study highlighted that socioeconomic vulnerability and limited access to healthcare services among Indigenous populations could increase the risk of infection-related cancers, such as HPV for cervical cancer, H. pylori for stomach cancer, and viral hepatitis for liver cancer [ 6 ]. Another study in the same region (Acre state) indicated that, compared to non-Indigenous populations, mortality rates for liver, stomach, colorectal cancers, and leukemias were more than double among Indigenous men; among Indigenous women, cervical, stomach, liver cancers, and leukemias were 30% higher [ 7 ]. Additionally, a study from the same Brazilian state showed a significant increase in breast cancer mortality rates but relative stability in cervical cancer rates from 1980 to 2014, highlighting concerns regarding healthcare access and follow-up [ 8 ]. Information on cancer in the Ecuadorian Amazon is equally scarce. A report covering 1985–1998 indicated lower cancer incidence rates in the Amazon region compared to Quito’s population. The age-standardized incidence rate was 39.49 per 100,000 men and 68.25 per 100,000 women. The most common cancers among men were stomach, skin, lymph nodes, hematopoietic system, and prostate; among women, cervical, stomach, breast, skin, and hematopoietic system cancers were predominant [ 9 ]. A subsequent update covering 1985–2003 observed an increase in cancer incidence during the first decade (1985–1994), followed by a decrease in the second (1995–2003). During the last period (2000–2003), the highest age-standardized annual incidence rates among women were for cervical (19.9/100,000) and stomach (5.9/100,000) cancers; among men, stomach cancer was most frequent, with 7.7 cases per 100,000 inhabitants [ 10 ]. An ethnic-comparative study conducted in 2002 revealed similar or even lower risks for various cancer types among Indigenous populations compared to non-Indigenous populations in the same Amazon region. Indigenous men exhibited lower risks for stomach, skin, prostate, lymph node cancers, and leukemia; similarly, Indigenous women had lower risks for stomach, skin, breast, cervical, and lymph node cancers [ 11 ]. These findings must be interpreted considering the limited access of indigenous populations to healthcare services and, consequently, to cancer registration. The limited existing literature underscores the urgency of updating cancer incidence data in Ecuador’s Amazon region. In this context, the present study aims to analyse trends in cancer incidence between 1990 and 2019, identifying the most prevalent cancer types and assessing their provincial hic and temporal distribution Methods Study design This study was designed as a retrospective, registry-based ecological analysis using data from the Quito Population-Based Cancer Registry. The unit of analysis was aggregated population-level cancer incidence data stratified by province, sex, age group, and five-year study period. The study population included residents of the Ecuadorian Amazon provinces of Sucumbíos, Orellana, Napo, and Pastaza diagnosed with cancer between 1990 and 2019 and registered in the NCR. Study population This study utilised data from patients diagnosed with cancer in Quito, whose habitual residences were in the Ecuadorian Amazon provinces of Sucumbíos, Orellana, Napo, and Pastaza. According to estimates from the National Institute of Statistics and Censuses (INEC in Spanish) for the year 2023, these provinces have a combined population of approximately 627,195 individuals, with women constituting 48.1%. Both Ecuador as a whole and these four provinces have experienced significant demographic shifts. Census data indicate a narrowing of the population pyramid base and an expansion of the older age groups. In 1990, 66.4% of the population in these provinces was under 25 years of age; by 2019, this proportion had declined to 54.4%. Conversely, the proportion of individuals aged 65 years or older increased from 2.3% in 1990 to 4.6% in 2019 [ 12 ]. The provinces of Morona Santiago and Zamora Chinchipe were excluded from the study due to their populations’ tendency to seek medical care in the Southern Highlands and Coastal regions, resulting in a low number of cancer cases recorded in the Quito NCR from these areas ( Fig 1 ). Download: PNG larger image TIFF original image Fig 1. Map of the study area; in pink, the four provinces of the study (created by the authors using geographic data from the Ecuadorian National Institute of Statistics and Censuses, available under a Creative Commons Attribution 4.0 International Licence). https://doi.org/10.1371/journal.pone.0359707.g001 Although each of the four provinces has a provincial-level hospital, none offers histopathological services or access to oncological treatment. In addition, no organized cancer prevention programmes are currently available in the region. Cancer data The Amazon region lacks its own cancer registries. Consequently, case ascertainment in the region depends heavily on referral pathways, access to specialized diagnostic services, and the capacity of patients to reach healthcare facilities in Quito, the nation’s capital. Geographic, socioeconomic, and healthcare access barriers may therefore contribute to incomplete case capture and differential underreporting across provinces and over time. All cases diagnosed in Quito are recorded in the Quito Population-Based Cancer Registry, which served as the data source for this study. The Quito Population-Based Cancer Registry collects information on all new cancer cases among patients whose habitual residence is in Quito. It also processes data on all cases diagnosed in Quito, regardless of the patient’s place of residence. The registry’s information sources include histopathological reports from pathology and haematology laboratories, as well as medical records from oncology care centres within the Public Integrated Health Network and the Complementary Network. Additionally, the Quito Population-Based Cancer Registry has access to hospital discharge and mortality data collected by INEC, facilitating the identification of new cancer cases. The registry is a member of the International Association of Cancer Registries (IACR) and adheres to the standards established by the International Agency for Research on Cancer (IARC), which set global criteria for assessing data quality and reliability [ 13 ]. Each individual record in the Quito Population-Based Cancer Registry includes a personal identification code, sex, age at diagnosis, cancer site, histology according to the International Classification of Diseases, 10th Revision (ICD-10), year of diagnosis, place of residence at diagnosis, and the patient’s educational level. This study included all cases recorded in the registry corresponding to the provinces of Sucumbíos, Orellana, Napo, and Pastaza during the period 1990–2019. Data were accessed on 1 October 2023. Based on the preceding information, we designed a population-based registry ecological study, with analyses stratified by province and time period. Ethics statement This study used anonymized data from the Quito Population-Based Cancer Registry database and adhered to the principles of good clinical practice (GCP) and the Declaration of Helsinki. Since participant identification was not possible but personal information was accessed, ethics committee approval was sought and granted by the SOLCA Quito Research Ethical Committee (reference OBS.23.216). Analysis Initially, the total number of cancer cases were calculated by sex, province, and study period. To ensure sufficient case numbers in each group, the analysis was structured into six five-year periods: 1990–1994, 1995–1999, 2000–2004, 2005–2009, 2010–2014, and 2015–2019. Subsequently, incidence rates for all cancers combined were estimated, stratified by sex. For the denominator in rate calculations, population data for the four provinces were used, stratified by sex and five-year age groups for each period. The estimated mid-period population, multiplied by five, served as the denominator. These data were obtained from INEC projections based on the national censuses of 1990, 2000, and 2010. Age-standardised incidence rates for all cancers combined were then calculated by province and period, using the direct standardisation method and Segi’s world standard population as the reference [ 14 ]. To better describe the current cancer burden, age-standardised incidence rates for the most recent period (2015–2019) were also calculated by province, for all cancers combined and the five most common cancer types, stratified by sex. Temporal trends in overall cancer incidence were assessed using quasi-Poisson regression models to account for overdispersion in the count data. The number of incident cancer cases was specified as the dependent variable, with the logarithm of the population included as an offset term. Calendar period was entered as an ordinal variable representing consecutive 5-year intervals, and models were adjusted for age group and sex. Incidence rate ratios (IRRs), 95% confidence intervals (CIs), and p-values for trend were estimated to quantify changes in incidence over time. All analyses were conducted using the open-source statistical software R [ 15 ]. Results Cancer incidence Between 1990 and 2019, a total of 5,008 cancer cases were recorded across the four Amazonian provinces of Sucumbíos, Orellana, Napo, and Pastaza. However, due to missing values in some variables, the analysis was based on 4,881 cases, 36.8% of which were men. The 127 missing cases were due to lack of information on age (n = 13) and the name of the province (n = 114). The data reveal a progressive increase in the number of recorded cases over successive five-year periods, culminating in a 357% rise between the first (1990–1994) and the last (2015–2019) study periods. While both sexes exhibited similar percentage increases, men experienced more pronounced rises during 1995–1999 and 2005–2009, whereas women showed greater increases in 2005–2009 and 2010–2014 ( Table 1 ). Download: PNG larger image TIFF original image Table 1. Total number of recorded cancer cases and percentage increase (in parentheses, relative to the preceding period) by period and sex. https://doi.org/10.1371/journal.pone.0359707.t001 The four most common cancer types by sex are detailed in Tables 2 and 3 . These cancers accounted for approximately 40% of all cases in men and 60% in women throughout the study periods. In men, the most frequent cancers were prostate, stomach, skin (non-melanoma), and lymphoid leukemia. A declining trend in stomach cancer incidence was observed, while prostate cancer showed a progressive increase over time. Among women, the predominant cancers were invasive cervical, breast, thyroid, cervical in situ, and skin (non-melanoma). A decrease in cervical cancer incidence was noted, whereas breast and thyroid cancers exhibited sustained increases. Download: PNG larger image TIFF original image Table 2. Number of cases and proportion (%) of the four most frequent cancers in men by period (ICD-10 codes in parentheses). https://doi.org/10.1371/journal.pone.0359707.t002 Download: PNG larger image TIFF original image Table 3. Numbers of cases and proportion (%) of the four most frequent cancers in women by period (ICD-10 codes in parentheses). https://doi.org/10.1371/journal.pone.0359707.t003 Age-standardised incidence rates Fig 2 illustrates the age-standardised incidence rates per 100,000 inhabitants for the entire Amazon region and each province across the study periods. Overall, there was a progressive increase in age-standardized cancer incidence rates for both sexes, with a more pronounced rise in the last three periods. Among men, the incidence rate escalated from 19 per 100,000 in 1990–1994–50 per 100,000 in 2015–2019, marking a 163.2% increase. For women, the rate rose from 37 to 96 per 100,000, reflecting a 159.5% increase. Detailed crude and age-standardised rates for the entire region and by province are available in S1 Table in S1 Appendix . Download: PNG larger image TIFF original image Fig 2. Annual average age-standardised incidence rates (adjusted to the world population) for the total Amazon region (four provinces) and each province. https://doi.org/10.1371/journal.pone.0359707.g002 While a general upward trend was observed across all provinces, variations were noted. In women, the provinces of Pastaza, Napo, and Sucumbíos experienced more significant increases in the last three periods. Similarly, in men, Napo and Orellana showed more pronounced rises in cancer incidence rates during recent periods. Most frequent cancers in 2015–2019 Table 4 presents the crude and age-standardised incidence rates per 100,000 inhabitants, along with 95% confidence intervals (CI), for the five most frequent cancers by sex during the 2015–2019 period. In men, prostate cancer was the most prevalent (8.3 per 100,000), followed by stomach cancer (5.4 per 100,000) and non-melanoma skin cancer (4.9 per 100,000). Among women, invasive cervical cancer was most common (18.2 per 100,000), followed by breast cancer (13.6 per 100,000) and thyroid cancer (11.8 per 100,000). Download: PNG larger image TIFF original image Table 4. Annual average crude and age-standardised incidence rates (per 100,000 inhabitants) with 95% confidence intervals for the five most frequent cancers by sex in the Amazon region during 2015–2019. https://doi.org/10.1371/journal.pone.0359707.t004 Trend test in overall cancer incidence In age- and sex-adjusted quasi-Poisson regression models, cancer incidence increased significantly over time, with an estimated 22.8% increase per 5-year period (IRR = 1.23, 95% CI 1.20–1.25). Overall, incidence was higher in women than in men (IRR = 2.00, 95% CI 1.88–2.14). However, a significant interaction between sex and period was observed (interaction IRR = 1.04, p = 0.050), indicating that incidence increased more rapidly in women than in men over the study period. Specifically, incidence rose by approximately 19.7% per 5-year period in men and 24.7% per 5-year period in women. Detailed estimates and their 95% CI are provided in S2 Table in S2 Appendix . Discussion This study provides an updated analysis of cancer incidence in the northern Amazon region of Ecuador from 1990 to 2019, utilizing data from the Quito Population-Based Cancer Registry. The findings indicate a significant increase in cancer incidence across the region, with notable rises in prostate, stomach, and non-melanoma skin cancers among men, and invasive cervical (malignant neoplasm of the cervix uteri), breast, and thyroid cancers among women. The observed upward trend, particularly pronounced in the last three five-year periods (2005–2019), underscores the urgent need for a comprehensive cancer control program in the region. The increase in cancer cases may reflect a combination of factors, including actual growth in disease prevalence, demographic shifts towards older age groups, improved cancer registration practices, and enhanced access to healthcare services.
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