For years, cancer drugs were developed to kill cancer cells without killing too many healthy cells.
Local medical oncologists say the latest drugs have added new approaches that include starving the cancer cells and enhancing the body’s own natural defense system.
“We continue to progress steadily and positively,” Dr. Ibrahim Sbeitan said at Conemaugh Cancer Care Center. “I don’t know if we can have a cure for cancer in our lifetime, but there is no question that we are going to find it.”
Medical oncology generally covers all cancer treatments involving drugs and chemotherapy. If the biopsies taken during surgery show that cancer has spread to the patient’s lymphatic system, in most cases the patient will receive drug treatment in addition to radiation therapy, Sbeitan said.
Although commonly grouped as “chemotherapy,” the traditional cancer drugs are just one area of medical oncology used today. The treatments, collectively referred to as systemic therapy, also include hormonal therapy and targeted therapy.
Hormonal therapy should not to be confused with menopausal hormone therapy using estrogen to help relieve symptoms. In breast cancer treatment, hormonal therapy uses agents that block hormones such as estrogen or progesterone because they promote the growth of some cancer types.
Targeted therapies use the body’s immune system to seek out and destroy certain breast cancer cells.
‘Starts from diagnosis’
Breast cancer treatment plans vary based on tumor size and the stage and type of the disease. The cancer’s genetic makeup, stage and risk of recurrence, along with the patient’s age and general health, are also considered.
The treatment varies for different cancer types, such as hormone-receptor-positive, triple-negative breast cancer or HER2-positive breast cancer. HER2 is a protein that promotes cancer growth.
Medical oncologists are routinely consulted even before cancer surgery, Sbeitan said. Together with the breast surgeon, the oncologists develop the course of treatment, including systemic therapy.
“The process starts from diagnosis,” he said in the cancer center at Conemaugh Memorial Medical Center. “We don’t treat every cancer the same.”
While normally associated with post-surgery treatment, systemic therapy can begin before surgery. Called neoadjuvant chemotherapy, these drugs help shrink a tumor before the surgical procedure.
There is currently research to determine if neoadjuvant chemotherapy can replace surgery for a few cancer patients, oncologist Dr. Rashid A. Awan, director of clinical services, said at UPMC Hillman Cancer Center in John P. Murtha Regional Cancer Center at 337 Somerset St., Johnstown.
The study at MD Anderson Cancer Center of the University of Texas is comparing the results of needle-guided biopsies with biopsies on tissue removed during lumpectomies after initial chemotherapy.
If the needle-guided biopsies prove as reliable as the post-operative biopsies in showing that the cancer was killed by chemotherapy, future patients may be able to avoid the surgery.
“That’s a big clinical trial,” Awan said at the Johnstown center. “If you prove the cancer is gone, there is no need to do surgery. You just do radiation therapy.”
Complex diseases, treatments
For patients whose cancer has spread to the lymph nodes, there are a variety of systemic therapies. A number of new therapy tweaks have recently been approved and more may be on the way, based on promising studies, Awan said.
He gave the example of triple-negative cancer, in which the three most common types of receptors known to fuel breast cancer growth are missing.
In the cancers that lack estrogen, progesterone and the HER2 receptors, common treatments such as hormone therapy and drugs that target those factors are not effective.
“Triple negative is the most difficult cancer to treat,” Awan said. “But we are starting to understand that this cancer is not one cancer, but six different cancers. They respond differently to different drugs.”
Awan predicts the discovery will lead to new protocols and testing for triple-negative cancer. He is already preparing his patient-education talk.
“OK you have a GM car – but is it a Buick, Chevrolet or Cadillac?” Awan said. “This is how we are able to explain it to our patients.”
Several PARP inhibitor drugs have shown promise in studies of women with triple-negative breast cancer, he said. The PARP inhibitors, including iniparib and olparib, interfere with the enzyme named poly ADP-ribose polymerase.
The enzyme normally fixes DNA damage in cells. But in cancer patients, it also fixes cancer cells damaged by chemotherapy medicines.
Cyclin-dependent kinases, or CDK, make up another group of drugs being explored for more applications in breast cancer patients, Awan said. By inhibiting the CDK enzymes, the body can better control its natural cell production.
“You interrupt the growth of the cancer cell by blocking the enzyme,” he explained. “The cancer cell can go and die.”
Although there is not as much current immunotherapy for breast cancer treatment as there is for other cancers, a drug called pembrolizumab is showing promise, he said.
The drug, also known as a checkpoint inhibitor, blocks the effects of a protein that normally keeps the body’s immune system in check.
By blocking the protein, the immune system is ramped up to naturally fight cancer throughout the body.
“In metastatic breast cancer, the good news is getting better and better by the day,” Awan said.
“There are more therapies and more options available than even two or three years ago.”
‘A chronic disease’
As cancer patients live longer, new treatments are also developed to deal with side effects of the cancer and the treatments, Dr. Sheetal Higbee said at Conemaugh Cancer Care Center.
“Survivorship is looking at cancer as a chronic disease,” Higbee said. “There are so many secondary effects – even secondary cancers.
“It is an emotional experience for everyone. It is something for you and your family to deal with for the rest of your lives.”
Each new advance brings science one step closer to the cure for cancer, Awan said.
“It is like a tree,” he said. “We are attacking different branches. Hopefully, we can get to the trunk.”
Awan believes changes in the body lead to cancer. Finding the root causes of those changes may be the key to finding a cure. He compares it to the “big bang” theory of the universe’s origin.
“Something caused the big bang to happen (in the body),” he said. “What is the big bang of cancer? What caused this gene to go abnormal?
“That will be the Holy Grail of cancer research.”