17. A chronic cough or chest pain

Leukemia and lung tumors (among others), show symptoms that can mimic a bad cough or bronchitis. Some patients also reported chest pain that extended to the shoulder and down their arms.
Cancer
18. Pelvic/Abdominal pain

Pain and cramping in the pelvis can be linked with the bloating signs of ovarian cancer. Leukemia also does this because it enlarges the spleen.
PainManagement
19. Pain in the back or lower right side

Often an early sign of liver cancer. Breast cancer can also be found through this as a breast tumor can press back into the chest or spread to the spine/ribs.
Cancer
20. Upset stomach

Stomach cramps or a frequently upset stomach can be a sign of colorectal cancer.