Pancreatic Cancer: Could Bacteria in our Mouth Help us Detect this Deadly Cancer Sooner?

By Jessica Cote

January 2013

 

Pancreatic cancer has one of the worst survival rates of all cancers: 94% of patients die within five years of diagnosis. Pancreatic cancer is the fourth-leading cause of cancer-related deaths in the U.S. and is expected to claim over 37,000 American lives in 2012.[1]

Early detection would improve survival rates

Like most cancers with low survival rates, pancreatic cancer is usually not diagnosed until after it has grown and spread to other parts of the body. Because the pancreas plays such a large role in the absorption of foods and the regulation of blood sugar levels, an advanced tumor in the pancreas severely impairs the digestive system and hormone regulation. When the cancer is finally found at this advanced stage, it can be very difficult to remove because the tumor has expanded into nearby blood vessels or organs such as the liver. For those lucky enough to discover the cancer early (only 10% to 15% of cases), tumors can be surgically removed, along with part or all of the pancreas (pancreatectomy).For the more than 80% of cases of pancreatic cancer that can’t be removed by surgery because it is too advanced, treatment includes radiation therapy, chemotherapy, or surgery to remove part of the pancreas, or a combination of the three.[2] These treatments don’t cure the cancer but they can help shrink tumors and slow the cancer’s spread.

Survival rates for pancreatic cancer patients could be greatly improved with a better method for finding and diagnosing the cancer at earlier stages. There is no simple screening test for pancreatic cancer, but new research suggests that testing for oral bacteria using a sample of saliva, gum or plaque might help doctors figure out who has the greatest risk of developing pancreatic cancer.

Could oral bacteria serve as a warning sign for pancreatic cancer?

A study by Dr. Dominique Michaud and colleagues at Brown University, published in 2012 in the journal Gut, focused on whether high levels of certain types of bacteria in the mouth could serve as a warning sign that a person might later develop pancreatic cancer.[3]

The researchers looked at health data from 519,978 people from 10 European countries, most of whom had provided blood samples as part of a study. Among the half million who participated in the study, 578 had developed pancreatic cancer, and these cancer patients had no additional malignant tumors except some had non-melanoma skin cancer. Only 405 of these patients had previously provided blood samples (five years prior to diagnosis, on average), so they were the focus of this study. The pancreatic cancer patients’ blood samples were compared with blood samples from 416 people of the same sex and close in age who didn’t have any cancer.

The blood samples were then tested for antibodies, or proteins produced by the immune system that would show whether or not certain types of bacteria had been present in the person’s mouth.

The people who were diagnosed with pancreatic cancer had higher amounts of three kinds of oral bacteria compared to people without pancreatic cancer. Perhaps most surprisingly, people who had one particular strain of bacteria in their mouth, called Porphyromonas gingivalis, were twice as likely to have developed pancreatic cancer compared to those without the bacteria. Because the blood samples of patients with pancreatic cancer were taken an average of five years before diagnosis of the cancer, it seems like the presence of these specific oral bacteria could serve as a warning sign for pancreatic cancer.

Some bacteria are harmless, and some bacteria are considered “good” rather than dangerous (such as those included in yogurt with active cultures or dietary supplements). People who had lots of harmless or good oral bacteria had almost half the risk of pancreatic cancer compared to those without such high levels of good bacteria.

Together with findings from other research studies, these results suggest that doctors may someday in the future prescribe good bacteria as a treatment, rather than antibiotics which kill bad bacteria. Good bacteria would likely be taken in the form of probiotics, which are supplements designed to reduce damage from antibiotics and other medicines and restore a healthy internal world of bacteria. Researchers are only beginning to learn about the ways bacteria can improve our health, and in what form to deliver good bacteria to people who need them.

What is Porphyromonas gingivalis?

In addition to its link to pancreatic cancer, P. gingivalis is a type of bacteria that is the major cause of periodontal disease, more commonly known as gingivitis or gum disease. Gingivitis is generally caused by long-term deposits of plaque on your teeth. The disease causes inflammation and infection that destroys the tissues around the gums and teeth. Common symptoms of gingivitis include bleeding gums, mouth sores, and sensitive or swollen gums.[4]

To make matters a bit more complicated, the 2012 study also found that some people with healthy gums had quite a bit of P. gingivalis in their mouths.[3] This means that the bacteria don’t always cause gingivitis and some people may have loads of P. gingivalis living in their mouth without knowing it. A doctor or dentist might need to perform a test using a sample of saliva, plaque or gum to locate the bacteria.

The researchers at Brown don’t fully understand the relationship between harmful oral bacteria and pancreatic cancer. For instance, they don’t know if oral bacteria like P. gingivalis lead to pancreatic cancer or if cancer in the pancreas somehow promotes the growth of P. gingivalis in the person’s mouth. Or perhaps both the cancer and the bacteria are the result of something else–an infection or some other assault on the body causing inflammation?

Perhaps most importantly, it is still unclear whether treating gingivitis more effectively can reduce the risk of pancreatic cancer, or whether you should get tested for pancreatic cancer if you find out that you have P. gingivalis bacteria. There are several ways to test for pancreatic cancer, but they can be expensive and invasive: you can get an MRI (magnetic resonance imaging) of your pancreas, a CT scan (computerized tomography) of your pancreas, or your doctor can use a scope to take a picture inside your body or take a biopsy (tissue sample) from your pancreas.

Since smoking, being overweight or obese, or having diabetes or long-term inflammation of the pancreas increase a person’s chances of developing pancreatic cancer, you can reduce your risk if you quit smoking, lose weight, and keep your diabetes under control-especially if you have P. gingivalis bacteria.

[5] If you have any of those risk factors and haven’t been to the dentist or periodontist lately, get a check-up and ask to be tested for P. gingivalis. Although medical experts aren’t completely certain how to remove these bad oral bacteria, they usually recommend flossing and brushing teeth regularly as well as rinsing with mouthwash as the best ways to get rid of them.

More research is needed to understand the link between oral bacteria and pancreatic cancer, and it will take medical experts some time still before they figure out how best to reduce the number of harmful bacteria in our bodies and increase the good kind.

The bottom line:

  • Pancreatic cancer is typically fatal because it is difficult to detect at an early stage. A method for earlier diagnosis would greatly improve chances for survival.
  • New research suggests that people who have a specific type of oral bacteria (P. gingivalis) are twice as likely to get pancreatic cancer as those without the oral bacteria. Also, people with lots of healthy oral bacteria have a much lower risk of pancreatic cancer than those without healthy bacteria.
  • Researchers still aren’t sure if harmful bacteria in the mouth cause pancreatic cancer or if the cancer wipes out healthy bacteria and leads to a person having harmful oral bacteria. More research will help clarify the connection between oral bacteria and pancreatic cancer.
  • Until then, take good care of your teeth and gums (brushing and flossing your teeth, and gently massaging your gums with a toothbrush) and see your dentist regularly. You’ll have a healthier mouth, and you might just have a healthier pancreas, too.

[1] Howlader N, Noone AM, Krapcho M, Neyman N, Aminou R, Altekruse SF, Kosary CL, Ruhl J, Tatalovich Z, Cho H, Mariotto A, Eisner MP, Lewis DR, Chen HS, Feuer EJ, Cronin KA (eds). SEER Cancer Statistics Review, 1975-2009 (Vintage 2009 Populations). National Cancer Institute. Bethesda, MD. http://seer.cancer.gov/csr/1975_2009_pops09/, based on November 2011 SEER data submission, posted to the SEER web site, April 2012.

[2] Sener SF, Fremgen A, Menck HR, Winchester DP. Pancreatic Cancer: A Report of Treatment and Survival Trends for 100,313 Patients Diagnosed from 1985-1995, Using the National Cancer Database. Journal of the American College of Surgeons 1999; 189(1):1-7.

[3] Michaud DS, Izard J, Wilhelm-Benartzi CS et al. Plasma antibodies to oral bacteria and risk of pancreatic cancer in a large European prospective cohort study. Gut 2012; 00:1-7.

[4] Gingivitis (Gum disease; Periodontal disease). In A.D.A.M. Medical Encyclopedia. PubMed Health: U.S. National Library of Medicine. Retrieved from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002051/

[5] Pancreatic carcinoma (Pancreatic cancer). In A.D.A.M. Medical Encyclopedia. PubMed Health: U.S. National Library of Medicine. Retrieved from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001283/