Racial and ethnic differences in risk of second primary cancers among prostate cancer survivors

Second primary cancer risks according to race and ethnicity among U.S. breast cancer survivors

Breast cancer survivors have an increased risk of developing second primary cancers, yet risks by race and ethnicity have not been comprehensively described. We evaluated second primary cancer risks among 717,335 women diagnosed with first primary breast cancer (aged 20-84 years and survived ≥1-year) in the SEER registries using standardized incidence ratios (SIRs; observed/expected). SIRs were estimated by race and ethnicity compared with the racial- and ethnic-matched general population, and further stratified by clinical characteristics of the index breast cancer. Poisson regression was used to test for heterogeneity by race and ethnicity. SIRs for second primary cancer differed by race and ethnicity with the highest risks observed among non-Hispanic/Latina Asian American, Native Hawaiian, or other Pacific Islander (AANHPI), non-Hispanic/Latina Black (Black), and Hispanic/Latina (Latina) survivors and attenuated risk among non-Hispanic/Latina White (White) survivors (SIRAANHPI = 1.49, 95% CI = 1.44-1.54; SIRBlack = 1.41, 95% CI = 1.37-1.45; SIRLatina = 1.45, 95% CI = 1.41-1.49; SIRWhite = 1.09, 95% CI = 1.08-1.10; p-heterogeneity<.001). SIRs were particularly elevated among AANHPI, Black, and Latina survivors diagnosed with an index breast cancer before age 50 (SIRs range = 1.88-2.19) or with estrogen receptor-negative tumors (SIRs range = 1.60-1.94). Heterogeneity by race and ethnicity was observed for 16/27 site-specific second cancers (all p-heterogeneity's < .05) with markedly elevated risks among AANHPI, Black, and Latina survivors for acute myeloid and acute non-lymphocytic leukemia (SIRs range = 2.68-3.15) and cancers of the contralateral breast (SIRs range = 2.60-3.01) and salivary gland (SIRs range = 2.03-3.96). We observed striking racial and ethnic differences in second cancer risk among breast cancer survivors. Additional research is needed to inform targeted approaches for early detection strategies and treatment to reduce these racial and ethnic disparities.

Variation in patterns of second primary malignancies across U.S. race and ethnicity groups: a Surveillance, Epidemiology, and End Results (SEER) analysis

PURPOSE

One in six incident cancers in the U.S. is a second primary cancer (SPC). Although primary cancers vary considerably by race and ethnicity, little is known about the population-based occurrence of SPC across these groups.

METHODS

Using Surveillance, Epidemiology, and End Results (SEER) 12 data and relative to the general population, we calculated standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for SPC among 2,457,756 Hispanics, non-Hispanic Asian American/Pacific Islanders (NHAAPI), non-Hispanic black (NHB), and non-Hispanic whites (NHW) cancer survivors aged 45 years or older when diagnosed with a first primary cancer (FPC) from 1992 to 2015.

RESULTS

The risk of second primary bladder cancer after first primary prostate cancer was higher than expected in Hispanic (SIR = 1.18, 95% CI: 1.01-1.38) and NHAAPI (SIR = 1.41, 95% CI: 1.20-1.65) men than NHB and NHW men. Among women with a primary breast cancer, Hispanic, NHAAPI, and NHB women had a nearly 1.5-fold higher risk of a second primary breast cancer, while NHW women had a 6% lower risk. Among men with prostate cancer whose SPC was diagnosed 2 to <12 months, NHB men were at higher risk for colorectal cancer and Hispanic and NHW men for non-Hodgkin's lymphoma. In the same time frame for breast cancer survivors, Hispanic and NHAAPI women were significantly more likely than NHB and NHW women to be diagnosed with a second primary lung cancer.

CONCLUSION

Future studies of SPC should investigate the role of shared etiologies, stage of diagnosis, treatment, and lifestyle factors after cancer survival across different racial and ethnic populations.

Causal relationship between prostate cancer and 12 types of cancers: multivariable and bidirectional Mendelian randomization analyses

BACKGROUND

Previous observational studies have shown an association between certain cancers and the subsequent risk of prostate cancer (PCa). However, the causal relationship between these cancers and PCa is still unclear. This study aimed to investigate the causal relationship between 12 common cancers and the risk of PCa.

METHODS

We employed genome-wide association studies (GWAS) to perform forward and reverse Mendelian randomization (MR) within two-sample frameworks. Furthermore, we conducted multivariable MR analyses to investigate the relationships between different types of cancer. In addition, multiple sensitivity analysis methods were employed to assess the robustness of our findings.

RESULTS

Our univariable MR analysis showed that genetically predicted hematological cancer was associated with a reduced risk of PCa (OR: 0.911, 95% CI 0.89-0.922, P = 0.03). Furthermore, MR analysis demonstrates that genetically predicted occurrence of thyroid gland and endocrine gland cancer also raised the risk of PCa (all P < 0.05). Multivariable analysis showed that thyroid gland cancer exhibited a higher incidence of PCa (OR: 1.12, 95% CI: 1.08-1.16, P = 0.008). In the reverse MR analysis, we found no significant inverse causal associations between PCa and 12 types of cancers.

CONCLUSION

In summary, this study provided insights into the causal relationships between various types of cancer and PCa. Hematological cancer was suggested to associate with a lower risk of PCa, while thyroid gland cancer and endocrine gland cancer might increase the risk. These findings contribute to the understanding of genetic factors related to PCa and its potential associations with other cancers.

Trends and age, sex, and race disparities in time to second primary cancer from 1990 to 2019

BACKGROUND

Despite the growth in primary cancer (PC) survivors, the trends and disparities in this population have yet to be comprehensively examined using competing risk analysis. The objective is to examine trends in time to second primary cancer (SPC) and to characterize age, sex, and racial disparities in time-to-SPC.

METHODS

A retrospective analysis was conducted based on Surveillance, Epidemiology, and End Results (SEER). Two datasets for this study are (1) the discovery dataset with patients from SEER-8 (1990-2019) and (2) the validation dataset with patients from SEER-17 (2000-2019), excluding those in the discovery dataset. Patients were survivors of lung, colorectal, breast (female only), and prostate PCs.

RESULTS

The 5-year SPC cumulative incidences of lung PC increased from 1990 to 2019, with the cumulative incidence ratio being 1.73 (95% confidence intervals [CI], 1.64-1.82; p < 0.001). Age disparities among all PCs remained from 2010 to 2019, and the adjusted HRs (aHRs) of all PCs were above 1.43 when those below 65 were compared with those 65 and above. Sex disparity exists among colorectal and lung PC survivors. Racial disparities existed among non-Hispanic (NH) Black breast PC survivors (aHR: 1.11; 95% CI: 1.07-1.17; p < 0.001). The types of SPC vary according to PC and sex.

CONCLUSIONS

Over the past three decades, there has been a noticeably shortened time-to-SPC among lung PC survivors. This is likely attributed to the reduced number of lung cancer deaths due to advancements in effective treatments. However, disparities in age, sex, and race still exist, indicating that further effort is needed to close the gap.