Changes in net survival rates happen slowly and in small amounts. Comparing the periods of 2003 to 2009 and 2010 to 2016, eight sites had a detectable change in their 5-year net survival rates.
We cannot say why the changes happened without a closer investigation. Better screening can improve net survival. But only 2 of the 7 with increased net survival also had an increase in the percentage of invasive cases caught at a localized stage: pancreatic cancer (7.4% from 2003 to 2009 diagnoses, and 8.9% from 2010 to 2016), and lung and bronchus cancer (15.0% from 2003 to 2009 diagnoses, and 17.4% from 2010 to 2016).
Prostate cancer had the only detectable decrease in 5-year net survival. A change in a screening recommendation in 2012 was possibly a part of this shift. The United States Preventive Services Task Force (USPSTF) recommended against routine screening for prostate cancer in men without symptoms. A decrease in screening could have delayed the diagnosis of prostate cancers until they reached a late stage and caused noticeable symptoms. For calculating the 2003 to 2009 net survival rate, 81.4% of the cases used were diagnosed at a localized stage. For the 2010 to 2016 rate, 76.2% were localized.
Pancreatic cancer is mostly diagnosed at a late stage (see the Stage section). But the 5-year net survival rate for pancreatic cancer increased a large amount for patients who caught it early.
Neither the USPSTF nor the American Cancer Society recommend patients without symptoms screen for pancreatic cancer. People should see a physician if they notice any of these symptoms (ACS 2019c):
Usually, these symptoms are caused by conditions besides pancreatic cancer.