COVID-19 in Cancer Patients, Risk Factors for Disease and Adverse Outcome, a Population-Based Study From Norway

Background

Cancer has been suggested as a risk factor for severe outcome of SARS-CoV-2 infection. In this population-based study we aimed to identify factors associated with higher risk of COVID-19 and adverse outcome.

Methods

Data on all confirmed SARS-CoV-2 positive patients in the period January 1 to May 31, 2020 were extracted from the Norwegian Surveillance System for Communicable Diseases. Data on cancer and treatment was available from the Cancer Registry of Norway, the Norwegian Patient Registry and the Norwegian Prescription Database. Deaths due to COVID-19 were extracted from the Cause of Death Registry. From the Norwegian Intensive Care and Pandemic Registry we retrieved data on admittance to hospital and intensive care. We determined rates of COVID-19 disease in cancer patients and the rest of the population. We also ran multivariate analyses adjusting for age and gender.

Results

A total of 8 410 patients were diagnosed with SARS-CoV-2 infection in Norway during the study period, of which 547 (6.5%) were cancer patients. Overall, we found similar age adjusted rates of COVID-19 in the population with cancer as in the population without cancer. Unadjusted analysis showed that patients having undergone major surgery within the past 3 months had an increased risk of COVID-19 while we did not find increased Odds Ratio (OR) related to other oncological treatment modalities. No patients treated with stem cell or bone marrow transplant were diagnosed with COVID-19. The fatality rate of COVID-19 among cancer patients was 0.10. This was similar to non-cancer patients, when adjusting for age and sex with OR (95% CI) for death= 0.99 (0.68–1.42). Patients with distant metastases had significantly increased OR of death due to COVID-19 disease of 9.31 (95% CI 2.60–33.34). For the combined outcome death and/or admittance to hospital due to COVID-19, we found significant two-fold increased risk estimates for patients diagnosed with cancer less than one 1 year ago (OR 2.08, 95% CI 1.14–3.80), for those treated with anti-cancer drugs during the past 3 months (OR 1.80, 95% CI 1.07–3.01) and for patients undergoing major surgery during the past 3 months (OR 2.19, 95% CI 1.40–3.44).

Cancer incidence in non-immigrants and immigrants in Norway

BACKGROUND

Major cancers are associated with lifestyle, and previous studies have found that the non-immigrant populations in the Nordic countries have higher incidence rates of most cancers than the immigrant populations. However, rates are changing worldwide - so these differences may disappear with time. Here we present recent cancer incidence rates among immigrant and non-immigrant men and women in Norway and investigate whether previous differences still exist.

MATERIAL AND METHODS

We took advantage of a recent change in the Norwegian Cancer Registry regulations that allow for the registry to have information on country of birth. The number of person years for 2014-2018 was aggregated for every combination of sex, five-year age-group and country of birth, by summing up each year's population in these groups. The number of cancer cases was then counted for the same groups, and age-standardised incidence rates calculated by weighing the age-specific incidence rates by the Nordic and World standard populations. Further, we calculated incidence rate ratios using the non-immigrant population as a reference.

RESULTS

Immigrants from Eastern Europe, the Middle East, Africa and Asia had lower incidence of total cancer compared to the non-immigrant population in Norway and immigrants born in the other Nordic or high-income countries. However, some cancers were more common in certain immigrant groups. Asian men and women had threefold the incidence of liver cancer than non-immigrant men and women. Men from the other Nordic countries and from Eastern Europe had higher lung cancer rates than non-immigrant men.

CONCLUSION

National registries should continuously monitor and present cancer incidence stratified on important population subgroups such as country of birth. This can help assess population subgroup specific needs for cancer prevention and treatment, and could eventually help reduce the morbidity and mortality of cancer.

Waiting times and treatment following cancer diagnosis: comparison between immigrants and the Norwegian host population

Background: There are concerns about timely access to appropriate cancer treatment for the growing immigrant population in Norway. This study aims to compare waiting times between cancer diagnosis and start of cancer treatment, as well as treatment patterns between immigrants in Norway and the host population.Material and methods: We performed a nationwide, registry-based study with individual-level data, including 213,320 Norwegians and 8324 immigrants diagnosed with breast, colorectal, lung or prostate cancer in 1990-2014. Differences in time from diagnosis to treatment and in treatment patterns were described for the selected cancer sites. The Cox and logistic regressions were used to adjust for patient and tumour characteristics.Results: After adjustment for covariates, hazard ratios for time from diagnosis to treatment for non-Western immigrants compared to Norwegians were 0.88 (95% confidence interval (CI): 0.82-0.95) for breast cancer and 0.84 (95% CI: 0.75-0.95) for lung cancer, indicating longer waiting times. Treatment patterns in the four major cancer sites were similar among immigrants and the Norwegian host population, except for breast cancer, where women from East and South Asia received less breast-conserving surgery than the Norwegian host population (adjusted odds ratios 0.65 (95% CI: 0.46-0.93) for East Asians and 0.75 (95% CI: 0.50-1.13) for South Asians).Conclusions: The present study reports delayed treatment for lung and breast cancer among immigrants from non-Western countries in Norway. Systematic differences in cancer treatment were not detected. However, less breast-conserving surgery among breast cancer patients from Asia compared to Norwegians was observed.

Differences in cancer survival between immigrants in Norway and the host population

Cancer survival is an important indicator for quality of cancer care. We sought to determine if there are differences in cancer survival between immigrants and the host population in Norway. We performed a nationwide registry-based study comprising subjects diagnosed with cancer between 1990 and 2014, and followed until the end of 2016. Survival was estimated for 13 cancer sites with cause-specific survival. Adjustments were made for common confounders (age, sex, year of diagnosis and place of residence) and defined mediators (stage at diagnosis, comorbidity and socioeconomic factors). A total of 500,255 subjects were available for analysis, of which 11,252 were Western and 8,701 non-Western immigrants. We did not find differences in cancer survival between Western immigrants and Norwegians, while non-Western immigrants, with some exceptions, had similar or better survival. Better lung cancer survival in non-Western immigrants than Norwegians was notable (hazard ratio (95% confidence interval): 0.78 (0.71-0.85)), and not explained by defined mediators. Immigrants from Eastern Europe and Balkan with melanoma (hazard ratio: 1.54 (1.12-2.12)) and prostate cancer (hazard ratio: 1.34 (1.08-1.67)), and possibly from sub-Saharan Africa with breast cancer (hazard ratio: 1.41 (0.94-2.12)) had worse survival than Norwegians. The results suggest that immigrants in Norway have good cancer survival relative to the host population. Poor survival in immigrants from Eastern Europe and Balkan with melanoma and prostate cancer, and sub-Saharan Africa with breast cancer might be a concern.

Melanoma staging: Varying precision and terminal digit clustering in Breslow thickness data is evident in a population-based study

BACKGROUND

Errors in Breslow thickness reporting can give misclassification of T category, an important classifier in melanoma staging.

OBJECTIVE

We sought to investigate precision (number of digits) and terminal digit clustering in Breslow thickness and potential consequences for T category.

METHODS

All first primary and morphologically verified invasive melanomas in Norway between 2008 and 2015 were included. A smoothing model was fitted to estimate the underlying Breslow thickness distribution without digit clustering.

RESULTS

Thickness was reported for 13,057 (97.5%) patients; the median was 1.0 mm (range, 0.09-85). It was reported as whole numbers (15.6%), to 1 decimal (78.2%) and 2 decimal places (6.2%)-thin tumors with more precision than thick tumors. Terminal digit clustering was found with marked peaks in the observed frequency distribution for terminal digits 0 and 5, and with drops around these peaks. Terminal digit clustering increased proportions of patients classified with T1 and T4 tumors and decreased proportions classified with T2 and T3.

LIMITATIONS

Breslow thickness was not reported in 2.5% of cases.

CONCLUSIONS

The Norwegian recommendation of measurement to the nearest 0.1 mm was not followed. Terminal digit clustering was marked, with consequences for T category. Pathologists, clinicians, and epidemiologists should know that clustering of thickness data around T category cut points can impact melanoma staging with consequent effect on patient management and prognosis.

Multimodal therapy is feasible in elderly anal cancer patients

BACKGROUND

Many patients are diagnosed with an anal cancer in high ages. We here present the outcome after oncological therapy for patients above 80 years compared with younger patients.

MATERIALS AND METHODS

A series of 213 consecutive patients was diagnosed and treated at a single institution from 1984 to 2009. The patients received similar radiation doses but with different techniques, thus progressively sparing more normal tissues. The majority of patients also had simultaneous [5-fluorouracil (5FU) and mitomycin C] or induction chemotherapy (cisplatin and 5FU). The patients were stratified by age above or below 80 years. Despite that the goal was to offer standard chemoradiation treatment to all, the octo- and nonagenarians could not always be given chemotherapy.

RESULTS

In our series 35 of 213 anal cancer patients were above 80 years. After initial therapy similar complete response was observed, 80% above and 87% below 80 years. Local recurrence rate was also similar in both groups, 21% versus 26% (p = .187). Cancer-specific survival and relative survival were significantly lower in patients above 80 years, 60% and 50% versus 83% and 80%, (p = .015 and p = .027), respectively.

CONCLUSION

Patients older than 80 years develop anal cancer, but more often marginal tumors. Even in the oldest age group half of the patients can tolerate standard treatment by a combination of radiation and chemotherapy, and obtain a relative survival of 50% after five years. Fragile patients not considered candidates for chemoradiation may be offered radiation or resection to control local disease.

Residual plots to reveal the functional form for covariates in parametric accelerated failure time models

We study residual plots for parametric accelerated failure time (AFT) models, using both standardized residuals and Cox-Snell residuals. Two different approaches are discussed in the case of censored data; adjusting censored residuals by adding a residual time, and using nonparametric exponential regression of non-adjusted censored Cox-Snell residuals. The main object of the paper is to show how residuals can be used to infer the correct functional form for possibly misspecified covariates. We demonstrate the use of the methods by analysis of two reliability data sets and by a simulation study using Weibull-distributed data. We also consider briefly a corresponding approach for parametric proportional hazards models.