Cancer treatments

By Jim Killackey, Staff Writer

Published: April 28, 2008

Cancer treatments have progressed as understanding of the disease’s foundation has evolved.

The classic way of doing things has been to remove the tumor and then blast the patient with radiation, chemotherapy or both to kill stray cells.

Now, some drugs attack cancer at its molecular soft spots, an approach called targeted therapy. The benefit is less damage to healthy cells than the scorched earth administration of chemotherapy.

Gleevec, which is used to treat a type of leukemia and some intestinal tumors, was the first approved drug to turn off the signal of a cancer-causing protein, according to the National Cancer Institute. Herceptin fights breast cancer by stopping cells from growing and dividing. Tarceva blocks a protein required for lung cancer tumor cells to grow and divide. Avastin blocks the formation of tumor-nourishing blood vessels in colon, lung and breast cancer.

Dr. Terence Herman, chair of radiation oncology for OU Physicians, noted that although classic chemotherapy drugs still are used widely, combining them with newer drugs that deal with the body’s response to cancer can improve patients’ odds.

“There are lots of targets that are now being looked at,” he said.

Some day, cancer treatment may be personalized and based on the genetic sequence of an individual tumor. This may not only prove to have fewer side effects for patients, but also may better attack cancer, which mutates rapidly to thwart its adversaries.

“After you give chemotherapy, the cancer has often evolved to be resistant to the chemotherapy,” said Doris Benbrook, a University of Oklahoma Health Sciences Center researcher who studies cancer.

Spending time with oncologists has taught Benbrook to appreciate the disease’s variety.

“I realize that every patient’s cancer is like a snowflake. It’s completely unique,” she said.

Chemotherapy

The classic way of treating cancer isn’t going anywhere. It’s effective and, compared to new drugs, cheaper.

Chemotherapy’s definition is simple: treatment with drugs that kill cancer. Living through it can be anything but simple. Because the drugs stop cancer cells from rapidly dividing, they also stop healthy cells in the mouth, intestines, blood and hair follicles from dividing. This leads to the hair loss, vomiting and some other common complications patients experience.

Heart, liver and kidney damage also are possible. Fatigue is common.

Drugs can be given many ways, including via injection, IV and as pills. Chemotherapy is given on a regular schedule or cycle, depending on cancer type and the person’s health. It can be given in a hospital, doctor’s office or in a patient’s home.

More than 100 drugs currently are used for chemotherapy, according to the American Cancer Society. The drugs work in various ways, such as by damaging DNA to prevent cancer cells from reproducing.

Not all cells in the tumor will have the same genetic mutations, so doctors give combination chemotherapy to kill as many of them as possible.

Dr. Patrick Gaffney, an oncologist and Oklahoma Medical Research Foundation researcher, said lymphoma patients often receive four anti-cancer drugs up front.

Gaffney predicted the “shotgun approach” to chemotherapy will be refined as a greater number of new drugs with cancer-specific effects become available. Because targeted therapy drugs often deal with ways cancer cells grow and communicate, they can be used for various cancers.

Doctors will prescribe them for patients if they think the drugs will be effective, even if the Food and Drug Administration hasn’t approved them for that use. The practice, called “off-label” use is legal and common.

“That’s kind of what drives all these clinical trials that are ongoing,” he said. “A lot of this just goes on at doctors’ offices.”

Gaffney, who has given chemotherapy to many patients, said things are much better than they used to be. Drugs are kinder on patients’ bodies, and anti-nausea medicines are effective.

“Twenty years ago, it was pretty bad,” he said.

More recently, many of his patients have been able to maintain active lifestyles and work while undergoing chemotherapy, he said.

Duncan resident Jim Edwards is one such patient. The 53-year-old builder had surgery for pancreatic cancer and then underwent chemotherapy and radiation therapy.

Unlike some cancer sufferers, he had few side effects from the treatments. He was nauseated once and was tired one day a week.

While undergoing chemotherapy, cancer patients often lose weight, and some are malnourished. Edwards was the opposite: He gained weight while receiving the drugs.

When his father underwent chemotherapy for lung cancer about 14 years ago, he was always sick from the toxic cocktail.

“Things have changed so much since then,” Edwards said.

Radiation therapy

Radiation is another standard of cancer eradication. About half of all cancer patients receive radiation therapy, either by itself or with another treatment, according to the National Cancer Institute.

Radiation kills cancer cells by damaging their DNA and rendering them incapable of dividing.

Radiation can be used to either kill a tumor or shrink it to relieve its symptoms.

Receiving radiation these days usually means less exposure to nearby tissue than in years past and delivery of a higher dose of tumor-killing energy where it needs to go.

Such “intensity-modulated radiation therapy,” in which scans are used to precisely deliver radiation, is now the standard of care.

The linear accelerator machines Herman uses also can treat small tumors by focusing energy into thin “pencil beams.” Along with a CT scan right before delivering the radiation, powerful computers allow the beams to reach the appropriate place even as the patient breathes and the tumor slightly moves.

Precision is particularly important in prostate cancer. The prostate is small and is surrounded by the bladder and rectum. A few centimeters can mean the difference between a successful treatment and irreparable burning, Herman said.

Brachytherapy, or the insertion of radioactive “seeds,” pellets or other items, has come a long way since it was first used to treat prostate cancer decades ago. Internal radiation therapy is now used on breast cancer, lung, cervical, ovarian and other cancers.

Surgery

The first line of attack against cancer remains removing the tumor surgically. Advances in tumor imaging and surgical techniques have allowed surgeons to operate with confidence on a growing number of patients.

Most people with cancer will have some type of surgery, according to the American Cancer Society.

“It’s an oft-forgotten critical first step,” said Dr. Alan Hollingsworth, medical director of oncology services for Mercy Health Center. “While a great deal of attention is given today to wonder drugs and high-tech approaches to cancer, we take for granted that the greatest leap in survival of this disease comes from the treatment that eradicates or removes the primary cancer.”

Surgeons may remove the entire tumor, or may “debulk,” or thin, tumors that can’t be removed without causing too much damage; such is often the case in ovarian cancer.

Surgery can be used to prevent cancer, such as when polyps are removed from the colon; to diagnose and stage cancer, often done using a biopsy; and to treat the discomfort or complications of cancer. Surgeons also often remove nearby lymph nodes to see if the cancer has spread.

Dr. Russell Postier, who chairs the surgery department at the OU College of Medicine, said he would love to see the day when surgery is an “archaic” way of treating cancer.

But, he said, “We’re a long way, unfortunately, from being able to do away with the scalpel.”

Postier predicted doctors will continue to refine the use of surgery, chemotherapy and radiation therapy together to best effect.

If doctors think a tumor has spread, they often won’t operate because of the risks to the patient and the likelihood stray cells will remain. One way doctors can tell if cells have spread is by using a PET (positron emission tomography) scan. PET scans distinguish cancer cells, which burn more sugar than regular cells to sustain their rapacious growth.

The American College of Chest Physicians last fall released revised lung cancer diagnosis, staging and treatment guidelines to reflect the improved chances for finding tumors and removing them surgically.

Small cell lung cancer is one type that surgeons seldom remove. Chemotherapy shrinks the tumors almost all the time, but they rebound quickly, Gaffney said.

A surgeon could remove the tumor but would be putting the patient at risk for infection, bleeding and anesthesia-related complications.

“Essentially, the gain is really very little,” Gaffney said of operating on these patients.

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