12.6: Treatment

When cancer is localized, removing it is a straightforward cure. Once cancer cells have spread, they are hard to destroy. Radiation and chemotherapy also affect normal cells (hence, side effects). Even these methods came about only as we learned how normal cells work.

Learning the details of how cells divide, scientists devise strategies to interfere with the rapid cell division that characterizes cancer. Fluorouracil is an anticancer drug. DNA production (needed for cell division) requires the base uracil (U). Fluorouracil competes with uracil, thus hampering the process.

Folate (a B-vitamin) is needed for cell division. Methotrexate hampers cell division by interfering with folate’s job, and is effective in treating such cancers as leukemia and cancers of the breast, ovaries, and bladder. But methotrexate hampers cell division in general, causing side effects where rapid cell division is normal. Side effects include anemia, gastrointestinal disturbances, and hair loss.

The goal of chemotherapy with methotrexate (and similar drugs) is to give a high enough dose to kill cancer cells while minimizing damage to normal cells.

For decades, scientists have been trying to devise ways to selectively destroy cancer cells—”magic bullets” that leave healthy cells alone. New ways to treat cancer have come from advances in immunology and biotechnology.

A major breakthrough in cancer treatment was for CML (chronic myelogenous leukemia) in 2001. CML is caused by an abnormal gene that produces an abnormal protein that causes the white blood cells to divide incessantly. The drug Gleevec (imatinib) blocks the action of that protein (a supremely targeted treatment). Before Gleevec, the 5-year survival for CML was 30%; it’s now 90%, with most of the patients living normal lives with normal life expectancies as long as they continue on the drug.

Monoclonal antibodies were discussed in relation to treating COVID-19 (chap. 10). Monoclonal antibodies are also used to treat some cancers. by targeting specific cancer cells to enable their destruction by one’s immune system.

Analysis of an individual’s genes is also being used with increasing success in determining the best treatment for that person’s cancer. Personalized and Precision Medicine and Pharmacogenomics are exciting and rapidly developing areas of research.

Survival Rates

How early cancer is detected and treated is the single most important factor in whether it’s curable. Thus, the location of cancer markedly affects survival. Non-melanoma skin cancer is highly curable, not only because it doesn’t spread fast, but also because it can be detected (and excised) promptly (left untreated, it can be fatal, like other cancers). Even though melanoma skin cancer spreads rapidly, the overall 5-year survival rate is 93% because it can be detected and treated relatively early.

If a cancer can’t be easily seen or felt, the next best thing is for the cancer to produce early signs that prompt a visit to a doctor. Blood in urine can be a sign of bladder cancer, and blood in stool can be a sign of colon, rectal, or anal cancer. However, the signs don’t necessarily mean cancer. Blood in stool can be from a bleeding ulcer in the digestive tract, blood in urine can be from a urinary tract infection, most lumps in the breast aren’t cancer.

Big advances in survival have been made with methods to detect cancer at its earliest stages. Introduction of the Pap test* as a way to screen for early stages of uterine/cervical cancer led to dramatically fewer deaths from this cancer (Table 12-1). Most cervical cancers are caused by sexual transmission of human papillomavirus. In 2006, a vaccine (Gardasil) was approved for prevention of this infection.

Cancers with the lowest survival rates are at sites that aren’t easily examined, or don’t usually produce symptoms until the cancer has spread. Warning signs of lung cancer are a persistent cough, sputum streaked with blood, chest pains, and recurring attacks of pneumonia or bronchitis. But some of these symptoms are just a more severe form of “normal” in heavy smokers, so lung cancer is usually found late. The 5-year survival is 22%.

Cancer of the ovary is typically “silent,” so it usually isn’t found until it has spread. If detected early, 5-year survival is 93%; if found late, it’s 30%. Pancreatic cancer is particularly grim (smoking is a major risk factor). It’s usually detected at an advanced stage. Overall 5-year survival is 11%. When diagnosed at an advanced stage, 5-year survival is 3%.

The American Cancer Society recommends regular checkups to screen for various cancers (see Appendix A-6 for sources of more detailed information). At what ages and how often people should be screened varies for different cancers and different family and personal histories.

You can do some screening on your own. Women are advised to examine their breasts monthly for lumps (for premenopausal women, the best time is at the end of menstruation when breasts are smaller). Men can feel for lumps in their testicles; this can be done conveniently while showering.

You can examine your skin for changes, especially changes in moles or nodules or the appearance of new ones. ABCD is for warning signs of melanoma: A for asymmetry (one half of the mole isn’t the same shape as the other half). B for border irregularity (edges are ragged, notched, or blurred). C for color (not uniform or is intensely black). D for diameter (wider than about ¼ inch and/or has grown suddenly or steadily).

^{*Physician George Nicolas Papanicolaou (1883-1962) devised this painless test. A few cells from the cervix and part of the vagina surrounding the cervix are removed with a swab and examined under a microscope.}