From Greek: para allelois beside one another. Lines are parallel if they lie in the same plane, and are the same distance apart over their entire length. Try this Drag any orange dot at the points P or Q. As the line PQ moves, the line RS will remain parallel to it. Parallel lines remain the same distance apart over their entire length.
It is important to know whether the cancer has got into the lymph glands because they are one of the main mechanisms by which the cancer can spread to other parts of the body. As long as the spread is just to the lymph glands near to the colon then this would indicate Stage 3 cancer.
1 A rectal exam and a blood test called a Prostate-Specific Antigen (PSA) test can find this cancer. The PSA test is free, and the digital exam has a 20% copay. Both are covered by Medicare once every 12 months.  Colon Cancer Screening: This cancer is more common in people over 50, and the risk increases with age.