survival trends: pancreatic cancer in the USA
STUDY BACKGROUND
Pancreatic cancer (PC) is a devastating malignancy with a 5-year survival rate of 10%. Despite accounting for only 3% of all new cancer diagnoses, it is the third leading cause of cancer-related deaths in the US. Surgical resection is the only potentially curative treatment for pancreatic tumors.
Pancreatic cancer is often diagnosed late. Hence, more than 80% of patients present with unresectable tumors, and the 5-year survival rate after resection is poor. In the global CONCORD-3 study, the 5-year survival rate of American pancreatic cancer patients improved from 7.2% in 2000–2004 to 8.9% in 2010–2014.
Despite inconsistent evidence on racial disparities, African Americans in the United States continue to have higher cancer incidence and mortality rates than whites. Further, previous research has noted higher overall survival among young males and in patients with localized tumors.
This study aimed to investigate survival trends by race, stage, age, and sex among pancreatic cancer patients (15-99 years old) in the US between 2001 and 2014.
METHODS
This population-based study included 399,427 adults diagnosed with pancreatic cancer during the 14 years 2001–2014. The data for this population-based study were from the third cycle of the CONCORD program.
This study included only primary, invasive tumors of the pancreas for survival analyses. Exclusion criteria included cases with ICD-O-3 codes 0 (benign tumor), 1 (uncertain or borderline malignancy), 1 (in-situ lesions), 6 (malignant, metastatic site), and 9 (malignancy with the uncertain metastatic site). Patients with missing or incomplete records, who didn’t fall between 15-99 years of age at diagnosis, and whose cancer registration was autopsy or Death Certificate Only (DCO).
To investigate the changes in treatment and survival, all eligible cases were divided into two groups based on their race (whites, blacks, and others) and stage at diagnosis (localized, regional, distant, or unknown). The cohort approach was used to estimate five-year survival for patients diagnosed during 2001–2003 and 2004–2008, because at least five years of follow-up data were available for these patients by December 31, 2014. The authors used a complete approach to estimate the survival of patients diagnosed during 2009–2014 because five years of follow-up data were available by the end of 2014.
Net survival (the probability of surviving cancer up to a given time) was estimated using the Pohar Perme estimator. Background mortality was analyzed from life tables specific for the race, region, sex, age, and calendar year. Net survival at 1 and 5 years by sex and stage at diagnosis was estimated for all patients and separately for blacks and whites. The International Cancer Survival Standard (ICSS) was used for standardizing net survival for all ages combined as well as for the age groups 15-44, 45-54, 55-64, 65-74, and 75-99 years.
RESULTS
- In total, this study comprised 399,427 pancreatic patients, among whom 50.4% were male and 49.6% female; 84.2% of patients were whites, 12.3% were blacks, 3.5% belonged to other ethnic groups, and 0.4% were of unknown races. Whites had a higher proportion of men than blacks (51.1% vs. 46.1%), as did patients aged 65–99 years (68.0% vs. 46.1%).
- About 9.5% of patients had localized disease, and 50.5% had the advanced disease; slightly more among black men.
- Across the study periods 2001–2003 and 2009–2014, the 1-year net survival rate increased from 25.6% (95% CI, 25.3%–26.0%) to 34.7% (34.5%–35.0%).
- The 1-year survival rate increased significantly in patients with both localized and regional diseases (10–12% vs. 53%), but it was much lower in cases with distant diseases and unknown stages (6-7%).
- Whites had higher one-year net survival than blacks (26.1% vs. 22.1% in 2001–2003 and 35.1% vs. 31.4% in 2009–2014). This distinction was more pronounced in men with localized or regional disease than in those at a later stage.
- 5 years after diagnosis, the survival gap between blacks and whites with localized disease remained, and it widened over time (from 24.0% vs. 21.3% in 2001–2003 to 39.7% vs. 31.0% in 2009–2014).
DISCUSSION
In this nationwide analysis of 399,427 pancreatic cancer patients, survival improved over time, particularly amongst patients with localized tumors. However, the results indicated a persistent disparity in one- and five-year survival rates between white and black patients. Several factors have been implicated in improved survival. For instance, a decrease in the proportion of patients who underwent diagnostic surgery, advanced diagnostic tools, and better preoperative evaluation.
Studies have reported gaps in accessing medical care, particularly among racial and ethnic minorities in the US. Also, there are inequalities in accessing private or public health insurance. As a consequence, blacks are more likely to face greater obstacles to cancer detection, surgeries, and survival. The authors acknowledged that this might be one of the reasons behind the poor one- and five-year survival outcomes reported in this study.
Contrarily, some studies, such as this one published in the Annals of Surgical Oncology, reported that race does not impact pancreatic cancer management or survival in an equal access health care system. A 2018 retrospective study among pancreatic cancer patients from Kaiser Permanente Southern California showed that racial and ethnic groups did not face barriers to getting care.
The results showed that black people were more likely than white people to have a tumor diagnosis at an advanced stage. In both blacks and whites, female survival was marginally higher than male survival. This was per Heather et al. and Martina et al., who found that non-whites and men have lower perceptions of cancer symptoms and risk factors than whites and women, respectively.
This, in effect, contributed to the survival advantage of black men over black women. The five-year survival estimates for localized, regional, and distant stages reported in this study were similar to those reported for the period 2009–2014.
CONCLUSIONS
In the US, survival among pancreatic cancer patients, particularly those who were diagnosed with a localized tumor, improved during 2001–2014. However, gaps in one- and five-year survival rates between blacks and whites were persistent through the same calendar period. This is likely due to disparities in access to cancer care, high-quality radical resection, and socioeconomic status.
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