Ductal carcinoma in situ, or DCIS, is a noninvasive breast cancer in which malignant cells are contained within the basement membrane. Treatment can involve breast-conserving surgery or mastectomy, with radiotherapy used after some breast-conserving operations. Researchers linked the Swedish National Quality Register for Breast Cancer with the Cause of Death Register, National Patient Register, Total Population Register and socioeconomic database to examine outcomes among women with primary DCIS treated in Sweden from 2008 through 2019. The three compared groups were breast-conserving surgery with radiotherapy, mastectomy without radiotherapy and breast-conserving surgery without radiotherapy.

Of the 7,165 women included, 3,821, or 53.3%, received breast-conserving surgery with radiotherapy; 2,381, or 33.2%, underwent mastectomy without radiotherapy; and 963, or 13.4%, received breast-conserving surgery without radiotherapy. The researchers stratified participants into ages below 60, 60 to 69 and 70 or older; 1,387 women, representing 19.4% of the cohort, were at least 70. Screening detection was more common below age 70, while comorbidity scores of two or more were more frequent among women aged 70 or older. Those receiving breast-conserving surgery with radiotherapy were also more likely to be married or partnered, have higher education and income, and have no recorded comorbidity.

During a median follow-up of 71.7 months for death, 383 participants died, including 40 whose death was attributed to breast cancer. The estimated 10-year overall survival for the full cohort was 90.4%, with a 95% confidence interval of 89.3% to 91.5%. It was 93.1% for breast-conserving surgery with radiotherapy, 88.0% for mastectomy without radiotherapy and 86.3% for breast-conserving surgery without radiotherapy. Estimated 10-year breast cancer–specific survival was 98.8% overall and was similar across the three groups. Because there were too few breast cancer deaths for further adjusted regression analysis, the principal survival comparisons evaluated death from any cause.

Results for the entire cohort depended partly on how missing data were handled. After stepwise adjustment for age, diagnosis year, region, histopathological extent, detection method, nuclear grade, education, family income, marital status, country of birth and comorbidity, mastectomy without radiotherapy was associated with higher overall mortality in the complete-case analysis, with a hazard ratio of 2.10 and a 95% confidence interval of 1.20 to 3.67. In the multiple-imputation analysis, however, the fully adjusted association was not statistically significant, with a hazard ratio of 1.29 and a 95% confidence interval of 0.95 to 1.76. The complete-case cohort also had fewer events and was selected toward later diagnosis years with shorter follow-up.

Breast-conserving surgery without radiotherapy was associated with higher overall mortality than breast-conserving surgery with radiotherapy in both analytical approaches after full adjustment. The hazard ratio was 2.68, with a 95% confidence interval of 1.34 to 5.34, in the complete-case analysis and 1.72, with a 95% confidence interval of 1.23 to 2.39, in the multiple-imputation analysis. A sensitivity analysis restricted to women with a comorbidity score of zero or one left the overall-death estimates largely unchanged. Another sensitivity analysis that censored follow-up at contralateral breast cancer produced somewhat stronger treatment associations, including a significant mastectomy association after adjustment for comorbidity in the multiple-imputation analysis.

The clearest age-specific survival pattern occurred among women aged 70 or older. In this group, mastectomy without radiotherapy was associated with higher overall mortality than breast-conserving surgery with radiotherapy in both analyses: the complete-case hazard ratio was 2.48, with a 95% confidence interval of 1.09 to 5.62, and the multiple-imputation hazard ratio was 1.89, with a 95% confidence interval of 1.23 to 2.90. Omission of radiotherapy after breast-conserving surgery was also associated with higher mortality among women aged 70 or older in the multiple-imputation analysis, with a hazard ratio of 2.32 and a 95% confidence interval of 1.47 to 3.68, although the corresponding complete-case estimate was not statistically significant. Among women aged 60 to 69, omission of radiotherapy was associated with higher mortality in both analyses. No significant overall-mortality difference among the three treatment groups was detected below age 60.

Local recurrence remained uncommon in absolute terms but followed a different pattern from overall survival. The study registered 318 local recurrences within 10 years: 204 after breast-conserving surgery with radiotherapy, 32 after mastectomy without radiotherapy and 83 after breast-conserving surgery without radiotherapy. The estimated 10-year local recurrence probability was 7.2% for the full cohort, with a 95% confidence interval of 6.3% to 8.0%. Local recurrence–free survival was 90.9% after breast-conserving surgery with radiotherapy, 97.8% after mastectomy without radiotherapy and 87.4% after breast-conserving surgery without radiotherapy. In adjusted multiple-imputation analyses, mastectomy was associated with lower recurrence risk than breast-conserving surgery with radiotherapy, with a hazard ratio of 0.18 and a 95% confidence interval of 0.11 to 0.28, while omission of radiotherapy was associated with higher risk, with a hazard ratio of 1.79 and a 95% confidence interval of 1.31 to 2.46.

The increased recurrence risk associated with omitting radiotherapy was most pronounced among women aged 60 or older. In contrast, the lower recurrence risk associated with mastectomy compared with breast-conserving surgery with radiotherapy remained statistically significant only among women below 60. An exploratory analysis applying NRG Oncology/RTOG 9804 risk criteria recorded eight local recurrences among 160 high-risk cases and five among 196 low-risk cases. Overall mortality did not differ significantly between those exploratory risk groups, with a log-rank P value of 0.23. The authors emphasized that the recurrence and overall-survival findings do not point in the same direction: mastectomy had the lowest observed recurrence risk, whereas breast-conserving surgery with radiotherapy combined a low absolute recurrence rate with the highest overall survival, particularly in older women.

Several limitations constrain interpretation of the registry analysis. Treatment was not randomized, and women in the three groups differed in education, income, screening detection and comorbidity, creating the possibility of residual selection bias. The study adjusted for measured patient, tumor and socioeconomic factors, but information on smoking, obesity, margin status and genetic susceptibility was unavailable. Multiple imputation addressed missing histopathological extent and nuclear grade under an untestable missing-at-random assumption. Register data also could not consistently distinguish noninvasive from invasive local recurrence or standard from oncoplastic breast-conserving surgery. The researchers therefore described the results as associations, not proof that breast-conserving surgery with radiotherapy causes superior survival. Within those limits, the study found favorable overall-survival outcomes and a low absolute recurrence risk for the combination, with the strongest observed survival associations occurring among women aged 70 or older.

Subject of Research: Age-specific overall survival and local recurrence after breast-conserving surgery, mastectomy and radiotherapy for ductal carcinoma in situ

Article Title: Age-specific survival after breast conservation versus mastectomy for ductal carcinoma in situ of the breast

Article References: de Boniface, J., Szulkin, R., Karlsson, P., & Johansson, A. L. V. (2026). Age-specific survival after breast conservation versus mastectomy for ductal carcinoma in situ of the breast. Breast Cancer Research and Treatment, 220(1), Article 10. https://doi.org/10.1007/s10549-026-08097-y

Image Credits: AI Generated

DOI: 10.1007/s10549-026-08097-y

Keywords: ductal carcinoma in situ, breast-conserving surgery, mastectomy, radiotherapy, overall survival, local recurrence, older women, Swedish cohort, observational study, population-based research, Age-specific, survival

Tailings storage facilities, known in the industry as TSFs, are the embankments and impoundments built to contain the fine-grained residue that remains after gold ore is crushed and processed. On the Witwatersrand, the gold-bearing basin that underlies much of Gauteng Province, these facilities rise as pale, treeless hills that dominate the horizon of townships and informal settlements. Under dry Highveld conditions, particularly during the windy winter months, fine dust can be lifted from tailings surfaces and carried into nearby communities. Residents may inhale respirable dust containing crystalline silica and, in some cases, low concentrations of uranium and other metals associated with gold-bearing ore. Assessing the health risks of such exposure requires not only measurements of dust concentration but also a clear picture of how long, and in what settings, people are actually exposed to whatever the wind carries off the dumps.

That second ingredient is precisely what time-activity data provide, and it is precisely what has been missing for the communities of the West Rand. Exposure assessment in environmental epidemiology depends fundamentally on the product of concentration and duration: a person who spends twelve hours a day outdoors near a dust source faces a very different exposure profile from someone who works in an office across town and sleeps behind closed windows. Yet regulatory models and risk assessments in South Africa, as in many countries, have often relied on generic assumptions imported from international guidelines, typically European or North American time budgets that assume substantial time indoors, in sealed buildings, with mechanical ventilation. Such assumptions map poorly onto communities where many homes are informal structures, where cooking and socializing happen outdoors, where unemployment keeps large numbers of people at home all day, and where children play on unpaved ground close to the tailings themselves.

The research team set out to replace those assumptions with locally observed data. Their study focused on residential communities situated in proximity to tailings storage facilities along the West Rand, the western arm of the Witwatersrand gold field that runs through municipalities such as Merafong and the areas around Randfontein and Westonaria. Participants across a range of age groups were asked to document and recall how they spent their time across a representative day, capturing the categories of activity that exposure scientists use to partition daily life: time indoors at home, time indoors elsewhere such as school or work, time outdoors near the residence, time spent further afield, and time in transit. By collecting this information separately for children of different ages, working-age adults, and older residents, the study was able to construct age-stratified time budgets rather than a single community average.

The age-stratified approach matters because exposure risk is not distributed evenly across a lifetime. Infants and young children breathe more air per unit of body weight than adults, their respiratory tracts are still developing, and their behaviors, crawling on floors, playing in dust, hand-to-mouth contact, can amplify contact with contaminated soil and particulates. School-age children spend large portions of the day in classrooms that may or may not offer protection from outdoor dust, and many walk routes to and from school that pass close to tailings footprints. Adults of working age may be away from the residential exposure zone for much of the day, or, where unemployment is high, may remain in it continuously. Elderly residents, particularly those with pre-existing respiratory or cardiovascular conditions, are among the most vulnerable to particulate pollution yet may spend nearly all of their time within a few hundred meters of home. Without age-specific data, a risk model that averages across these very different patterns will underestimate exposure for some groups and overestimate it for others.

While the detailed numerical results reside in the full publication, the study’s contribution can be understood at two levels. At the level of raw evidence, it provides measured, locally grounded estimates of the hours per day that West Rand residents of different ages spend in locations and microenvironments relevant to tailings-derived dust exposure. At the level of method, it demonstrates a practical protocol for gathering such data in resource-constrained, high-exposure settings, where survey-based recall and structured questionnaires are often the only feasible instruments. Studies of this kind commonly reveal that total time outdoors near the home is substantially higher than default values assumed in international exposure models, particularly for children and for adults who are not formally employed, and that time in enclosed, mechanically ventilated environments is correspondingly lower. The West Rand findings are significant precisely because they anchor risk calculations in the actual rhythms of life in mining-adjacent communities rather than in borrowed assumptions.

The broader context makes the work urgent. The Witwatersrand has produced gold since 1886, and the region’s legacy tailings footprint extends across hundreds of square kilometers, much of it now surrounded or penetrated by residential development that expanded during and after apartheid-era planning, when Black communities were frequently located on marginal land close to mine dumps. Re-mining operations, in which companies reprocess old tailings to extract residual gold, add a contemporary layer of activity: trucks, conveyors, and processing plants that can re-suspend dust from deposits that had partially stabilized. Community organizations and environmental justice groups on the West Rand have for years raised concerns about respiratory illness, silicosis-like symptoms, and the long shadow of mining waste, while regulatory attention to residential proximity has grown through frameworks such as South Africa’s National Environmental Management Act and guidelines addressing buffer distances around tailings facilities. Sound policy in this contested space depends on defensible exposure estimates, and defensible exposure estimates depend on exactly the kind of time-activity data this study supplies.

The findings also speak to an international audience of exposure scientists, because time-activity patterns are among the most context-dependent variables in all of environmental health research. A time budget measured in a North American suburb, with its sealed houses, air conditioning, and car commutes, is simply a different object from one measured in a settlement of informal dwellings where daily life unfolds outdoors. Researchers in the exposure sciences have increasingly recognized that microenvironment models, which calculate total exposure as the sum of concentrations multiplied by time spent in each distinct setting, are only as good as the time-location inputs they receive. Studies from low- and middle-income countries remain underrepresented in this literature relative to the size of the populations potentially affected, which makes locally generated datasets from places like the West Rand valuable well beyond their immediate geography. They offer reference points for other mining-affected regions of southern Africa, and for the wider Global South, where tailings facilities and residential communities frequently coexist.

For residents themselves, the practical significance lies in what follows from measurement. Age-specific time budgets can inform where and when dust-control interventions will deliver the greatest benefit: rehabilitating tailings surfaces with vegetation or covers, adjusting re-mining activities during high-wind seasons, considering buffer zones in land-use planning, and targeting school and household-level measures, such as improved ventilation practices and dust-suppression around play areas, toward the groups whose daily routines place them most directly in the exposure pathway. Public health authorities can use the same data to refine health risk assessments and to prioritize environmental monitoring locations. Community advocates gain a documented, quantified account of how mining infrastructure shapes the daily lives of those living in its shadow, evidence that can carry weight in consultations, licensing processes, and debates over land use.

The study also underscores a deceptively simple point that recurs throughout exposure science: people are not passive receptors of pollution, and the dose they receive reflects the texture of their days. Understanding that texture, hour by hour and age group by age group, is an unglamorous but essential foundation for protecting public health in landscapes shaped by extraction. For the communities of the West Rand, where gold mine waste has been a neighbor for generations, having their actual patterns of movement and activity captured in the peer-reviewed literature represents a step toward risk assessments that see them as they are. It is a reminder that the path from a mine dump to a person’s lungs runs not only through the air, but through the ordinary details of where people live, work, learn, and play, and that measuring those details is where credible environmental health protection begins.

As gold mining continues its long retreat across the Witwatersrand, the waste it leaves behind will outlast the industry itself, and the populations living alongside that waste will continue to grow. Research that documents, with precision, how those populations inhabit their environment converts a legacy of neglect into an evidence base for action. The age-specific time-spent patterns reported for the West Rand provide a template for how such evidence can be gathered and a foundation on which dust management, urban planning, and public health interventions can now be built, in South Africa and in every other region where communities and mine tailings share the same ground.

Subject of Research: Age-specific time-spent patterns among residents living near gold mine tailings storage facilities in the West Rand, South Africa

Article Title: Age-specific time-spent patterns among residents living near gold mine tailings storage facilities in the West Rand, South Africa

Article References: Kalumbi, L. R., Masekameni, M. D., Utembe, W., & Brouwer, D. (2026). Age-specific time-spent patterns among residents living near gold mine tailings storage facilities in the West Rand, South Africa. Journal of Exposure Science & Environmental Epidemiology. https://doi.org/10.1038/s41370-026-00972-6

Image Credits: AI Generated

DOI: 10.1038/s41370-026-00972-6

Keywords: Age-specific, time-spent, patterns, residents, living, near, gold, mine, tailings, storage, facilities, West