What Purpose Does Chemotherapy Have in Pancreatic Cancer?

The Benefits and Drawbacks of Chemotherapy

The most common type of pancreatic cancer is known as adenocarcinoma of the pancreas. Other cancers that originate in the pancreas can include neuroendocrine tumors and lymphoma. The treatment and prognosis is very different across these different types.

Chemotherapies specifically are used in a variety of ways to treat cancer of the pancreas, including following potentially curative surgery.

Benefits of Chemotherapy After Surgery

What benefit does chemotherapy have following surgery?

Before proceeding, it is to be noted that the majority of patients are typically not candidates for surgery for a variety of reasons. The idea behind surgery for pancreatic cancer is to physically remove all cancer cells. If every cancer cell is removed, the cancer is eradicated and the patient is cured.

The problem, however, lies in the impossibility of being able to visualize microscopic residual cancer. The human body is comprised of an enormous number of cells (in the trillions) and there is not currently a practical way to detect any residual cancer cells. A surgeon can't see them and they won't show up on imaging studies, including CT or PET scans. Therefore, the idea behind chemotherapy is to destroy any residual cancer cells that aren't seen.

Which Chemotherapies Are Used?

So which chemotherapy is used and why? Chemotherapies are used after they have passed through clinical trials which demonstrate not only effectiveness but also safety.

The prognosis for pancreatic cancer is poor so new treatment approaches, including other chemotherapies, are always under investigation. Currently the chemotherapy with the greatest benefit following surgery for pancreatic cancer is a chemotherapy known as gemcitabine.

Before discussing the benefit of chemotherapy, it is important to understand how cancer research is performed.

Cancer treatments are approved and used once undergoing clinical trials to show that they are both safe and effective. Later phase cancer trials typically have at least two arms (groups of people). In one arm, an established treatment or placebo is used. In the other arm, a new treatment approach is used.

Researchers evaluate for certain end points. Common end points in cancer research are progression free survival, overall survival and 5-year survival rates. Progression free survival is just as it sounds: the amount of time the person lives without any evidence of progression. Progression is defined in several ways including tumor growth, increasing tumor markers or new/worsening symptoms from the cancer.

Overall survival is also self-explanatory: how long someone lives since starting the trial. Both progression free survival and overall survival are measured using medians rather than averages. Cancer research typically utilizes medians over averages because, depending on the outcome being measured, it could take decades for all outcomes to occur so an average could be calculated.

5-year survival rates simply show what number of people are alive at 5 years from treatment.

Gemcitabine: The Benefit

Gemcitabine was initially approved given the benefit of what is called progression free survival.  Compared to no treatment following surgery(i.e., the control arm), those who received gemcitabine (the treatment arm) had a median progression free survival of 13.4 months compared to a progression free survival of 6.7 months for those who did not. Further follow-up showed those treated with gemcitabine following chemotherapy offered a survival advantage. At 5 years 20.7 percent of the gemcitabine arm were still alive versus 10.4 percent of the control arm.

Gemcitabine: The Drawbacks

Gemcitabine has several drawbacks. First of all, roughly 80 percent of people that receive it will have their cancer come back and eventually succumb to it. It's far from a guarantee of curing the cancer. Secondly, it is not without side effects.  The most common ones include nausea, vomiting, low white blood cells predisposing to infection, low platelets predisposing to bleeding problems, diarrhea, rashes and fever to name a few. To be able to receive gemcitabine, the person needs to be in relatively good health.

Gemcitabine: How It's Given

Gemcitabine is administered intravenously once every week for 3 weeks with the 4th week off. This 4 week period is known as a cycle. This is typically done for 6 cycles, taking nearly 6 months to complete the treatment. It should be administered with anti-nausea medications to limit the severity of nausea.

Gemcitabine: The Bottom Line

Pancreatic cancer is aggressive with fewer than 10 percent of those diagnosed still alive at 5 years. Although gemcitabine therapy is a far cry from curing the majority of those treated, it does offer potential cure to a significant number of people who would not have had it otherwise. Whether or not an individual can and should have chemotherapy for pancreatic cancer is a conversation that needs to happen with an experienced medical oncologist.

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