Multi-generational SIR modeling: Determination of parameters, epidemiological forecasting and age-dependent vaccination policies.

We use an age-dependent SIR system of equations to model the evolution of the COVID-19. Parameters that measure the amount of interaction in different locations (home, work, school, other) are approximated from in-sample data using a random optimization scheme, and indicate changes in social distancing along the course of the pandemic. That allows the estimation of the time evolution of classical and age-dependent reproduction numbers. With those parameters we predict the disease dynamics, and compare our results with out-of-sample data from the City of Rio de Janeiro. Finally, we provide a numerical investigation regarding age-based vaccination policies, shedding some light on whether is preferable to vaccinate those at most risk (the elderly) or those who spread the disease the most (the youngest). There is no clear upshot, as the results depend on the age of those immunized, contagious parameters, vaccination schedules and efficiency.

Sentinel Lymph Node Biopsy in Patients With Acral Melanoma: Analysis of 201 Cases From the Brazilian National Cancer Institute.

BACKGROUND: Sentinel lymph node biopsy (SLNB) is the most powerful predictor of relapse-free survival (RFS) and overall survival (OS). No studies have evaluated survival of acral melanoma (AM) undergoing SLNB in Brazil. OBJECTIVE: The objective of this study was to investigate the factors associated with the survival of patients with AM undergoing SLNB. MATERIALS AND METHODS: Patients diagnosed with AM and submitted to SLNB were included in this study. We evaluated the epidemiologic, clinical, and histopathological data. Overall survival and RFS curves were estimated using the Kaplan-Meier method. Multivariable analyses were conducted using the Cox regression model. RESULTS: Among the 201 patients, 117 (58.2%) were female. The median age was 64 years old. Median tumor depth was 5.0 mm. Lesions were ulcerated in 134 (66.7%). Five-year OS and RFS rates were 44.6% and 38.6%, respectively. Median follow-up time was 39 months. The factors associated with OS were Breslow thickness, ulceration, and SLNB status, and for RFS, they were Breslow thickness and SLNB status. CONCLUSION: This is the largest series of AM submitted to SLNB. The 5-year OS and RFS rates were low (44.6% and 38.6%, respectively), and the main prognostic factors for OS were Breslow thickness, ulceration, and the status of SLNB.

Subungual melanoma: A retrospective cohort of 157 cases from Brazilian National Cancer Institute.

BACKGROUND: Subungual melanoma (SM) is rare. The lesions are thick at the time of diagnosis. Few studies have evaluated SM in Brazil. OBJECTIVE: The objective of this study was to investigate the factors associated with the survival of SM patients from the Brazilian National Cancer Institute. METHODS: One-hundred and fifty-seven patients diagnosed with SM were included in this study. We evaluated the epidemiologic, clinical, and histopathological data. Overall survival (OS) and relapse-free survival (RFS) curves were computed using the Kaplan-Meier method. Multivariable analyses were conducted using the Cox proportional hazard regression model. RESULTS: Among the 157 patients, 87 (55.4%) were female. The median age was 68 years old. Median tumor depth was 6.0 mm. Lesions were ulcerated in 94 (59.9%). OS and RFS rates for 5 years were 61.0% and 41.8%, respectively. Median follow-up time was 28 months. The factors associated with OS were Breslow thickness and ulceration, and for RFS, they were the anatomical site, Breslow thickness, and ulceration. CONCLUSION: This is the largest series of SM patients. The 5-year OS and RFS rates were low (61.0% and 48.2%, respectively), and the main prognostic factors for OS were Breslow thickness and ulceration.

Mortality frequency and trends attributed to melanoma in Brazil from 1980-2005.

Melanoma is the leading cause of skin cancer deaths in Brazil, and accounts for 1% of cancer deaths. This study aimed to analyze mortality attributed to melanoma in Brazil during the period 1980-2005, for the population as whole and with respect to the age, gender, and geographical patterns of distribution, and the data were subsequently compared to melanoma frequency rates observed in other countries. Annual age-standardized mortality rates were ascertained for all regions with data provided by the National Mortality System. An exploratory analysis using log-transformed Poisson regression was conducted, and changes in mortality trends during this period were evaluated. Then the best-fitted trend model, ascertainment of the annual average percentage change (AAPC) during 1980-2005, was identified. Mortality associated with melanoma in Brazil increased during the period studied, with the APCC for the whole country being 1.1%. The rate was highest among the elderly: APCC 2.8% in those over 70 years old and 2.3% in females. The mortality ratio comparing South and North regions was 7 in 2005. An increase in mortality frequency associated with melanoma occurred in Brazil since 1980, with different patterns noted by gender, age and region. The observed results highlight the relevance of and need for public health policies toward skin cancer control.