Among the top suspects are man-made chemicals that interfere with the immune system. As far back as the 1970s, scientists observed that the highest rates of non-Hodgkin's lymphoma occur in farmers. This observation has led many investigators to examine the effects of insecticides, fungicides and herbicides.

Subject:     non-Hodgkin's Lymphoma------------
 Date:       Thu, 02 Dec 1999 17:36:18 -0500
From:     Stephen Tvedten <steve@getipm.com>
Organization:     Get Set Inc. (www.getipm.com)
To:     Lyndon Hawkins <hawkins@empm.cdpr.ca.gov>

Lyndon - Did you read about the TROUBLING TREND?  Among major cancers, increases in only one remains a mystery.
By Laura Beil / Public Health Writer of The Dallas Morning News Published 09-27-1999.  Non-Hodgkin's lymphoma is one of the few diseases named for something it isn't. Now if scientists could just understand what it is.

Of all major types of cancer that affect Americans, only non-Hodgkin' s lymphoma has dramatically risen for no apparent reason. Unlike many other common malignancies, non-Hodgkin's lymphoma has no long list of risk factors and no recommended screening tests.

Yet it has quietly and steadily hoisted itself from relative rarity, becoming the fifth-most common cancer among men, and sixth among women. "The increase has been phenomenal," said Shelia Zahm, a scientist with the National Cancer Institute. During the last quarter-century, U.S. rates have increased 95 percent for men and 63 percent for women. An estimated 56,000 new cases will be diagnosed in 1999.

And the numbers show no signs of slowing down soon, she said.

A small part of the increase can be explained by better diagnosis of the cancer, and by some association with the AIDS epidemic. But most of the trend, Dr. Zahm said, "is just basically left unexplained."

Scientists are not without theories. Some experts suspect a silent viral infection churning through the population. Other researchers are examining whether the disease might be triggered by Americans' exposure to chemicals in the environment. And some evidence even implicates the high-meat, high-protein diet of Western countries as a contributor to the disease.  There's also research into sunlight exposure, black hair dyes, physical activity levels and a host of lesser possibilities that can affect the immune system.

"I can't think of anything that's been totally ruled out," said Dr. James Cerhan of the Mayo Clinic in Rochester, Minn. The final answer, he said, will probably turn out to be a combination of influences. (Synergism, Lyndon is what Californians have a lot of.)

In a search for clues, Dr. Zahm and her colleagues have recently embarked on the largest study of non-Hodgkin's lymphoma ever undertaken. For the next two years, they hope to recruit 1,200 patients into the study. Those patients will be compared with 1,200 people of the same age and gender who do not have the disease.

"I think we'll figure it out," Dr. Zahm said.

Like other cancers, non-Hodgkin's lymphoma is a disease of aging.  Jacqueline Kennedy Onassis was 64 when she died of non-Hodgkin's lymphoma, and King Hussein of Jordan was 63.

The disease gets its name from its counterpart, Hodgkin's disease.  Hodgkin's disease is a kind of lymphoma that involves the production of unusually large, cancerous cells called Reed-Sternberg cells; the term non-Hodgkin's lymphoma encompasses most other lymphomas. Rates of  Hodgkin's disease have declined.

Much of the investigation into the cause of non-Hodgkin's lymphoma focuses on elements that might affect the immune system. This is because the cancer itself involves lymphocytes, the ground troops of the body' s immune system. Something that weakens these cells, or, alternatively, keeps them revved up, might interfere with the mechanisms that restrain immune cells from growing uncontrollably and thereby becoming cancerous.

Severe immune suppression is probably why people infected with the human immunodeficiency virus are at increased risk for the cancer. But HIV can account for only a small fraction of new non-Hodgkin's lymphoma patients.

Among the top suspects are man-made chemicals that interfere with the immune system. As far back as the 1970s, scientists observed that the highest rates of non-Hodgkin's lymphoma occur in farmers. This observation has led many investigators to examine the effects of insecticides, fungicides and herbicides.

And in farmers, repeated exposure to chemicals does appear to pose a risk, studies have found.

Although farmers make up only a small fraction of the population, and therefore in themselves can't account for the higher numbers of people who get the cancer, the use of pesticides in and around homes has increased during the last half of this century. Figures from the Environmental Protection Agency suggest that residential sales of pesticides have almost doubled since 1978.

"But we don't know if the very low levels that people are exposed to can confer risk," Dr. Zahm said.

Studies so far have suggested that chemicals may indeed have a role in the disease. For example, a Swedish study published last March in the journal Cancer found that exposure to herbicides, and fungicides in particular, appeared to increase the risk of non-Hodgkin's lymphoma.

"The data are quite strong, I would say. There are so many studies by now," said Dr. Lennart Hardell of the Orebro Medical Center in Orebro, Sweden. "There is an association between at least certain pesticides and non-Hodgkin's lymphoma."

But while some pesticides - especially some herbicides - look suspicious, the research is still too unclear to indict any specific chemicals, Dr. Hardell said.

Dr. Zahm also cautioned against making conclusions just yet. In 1997, for instance, she and her colleagues published a small study in the journal The Lancet hinting that PCBs might be involved in the disease.  The report concluded with a refrain of many non-Hodgkin's lymphoma studies: "Before causal inference can be made . . . the association needs further investigation."

One of the biggest difficulties with pesticide studies in the general population is that a person's exposure to the chemicals is very hard to measure.

And even if a study finds that people are exposed, it's difficult to say whether that chemical caused their disease.

That's one of the questions faced by lymphoma researchers who are studying viruses - does the virus hijack a cell and turn it malignant, or just hitch a ride on an already malignant cell? The tumors of many patients with non-Hodgkin's lymphoma have been found to contain any one of a host of viruses. Often the virus is the one called Epstein- Barr, which is found in saliva and can spread from person to person. It now ranks at the top of the list of viral suspects in non-Hodgkin' s lymphoma.

"It's actually a ubiquitous virus to which a lot of people are exposed by adult age," said Dr. Angela Manns of the National Cancer Institute's division of viral epidemiology. While scientists don't yet know how it might affect otherwise healthy adults, "in settings where people are immune-compromised, Epstein-Barr seems to play a role in the development of non-Hodgkin's lymphoma."

In Africa and New Guinea, the virus is also thought to play a role in a kind of lymphoma, known as Burkitt's lymphoma, that commonly affects children.

Epstein-Barr isn't the only virus under suspicion. Human herpes- virus 8; the virus associated with the AIDS-related Kaposi's sarcoma; hepatitis C; and a virus known as HTLV are also being studied.

"I don't know if any of these viruses are going to account for the increasing incidence, but it may be one factor," Dr. Manns said.

The bacterium Helicobacter pylori, famous for causing ulcers, may also lead to the development of one kind of non-Hodgkin's lymphoma associated with the digestive system, recent studies have suggested. In 1993, researchers writing in The Lancet reported that antibiotics that wiped out the bacterium also sent the lymphoma into retreat.

Other scientists are also looking to the digestive system for answers, but they're not hunting for viruses or bacteria. They're looking at food.

"The diet hypothesis is out there for a couple of reasons," said Dr. Cerhan of the Mayo Clinic. For one thing, "there seems to be some strong correlations going on with protein consumption."

Also, proteins found in food engage in a complicated dance with the immune system - the body is normally programmed to attack foreign proteins, but that doesn't happen if those proteins are part of dinner.  In a 1996 study published in The Journal of the American Medical Association, Dr. Cerhan and his colleagues reported that a diet high in protein, and especially red meat, seemed to raise the risk of non-Hodgkin's lymphoma. Studies of heavy milk consumption have also suggested a link.

And this year, researchers from Harvard University reported that among more than 84,000 women, those who ate beef, pork or lamb as a main dish once a day had a higher risk of non-Hodgkin's lymphoma than those who ate meat less than once per week. The results were presented in April during a meeting of the American Association for Cancer Research.

"I think in the long run that diet is going to be an important player,"  Dr. Cerhan said, adding that a majority of scientists probably disagree with him at this point.

Probably several theories will turn out to be correct, said Dr. Jim Armitage, a cancer specialist at the Nebraska Medical Center. Non-Hodgkin's lymphoma isn't just one disease - it affects immune cells at different stages of development - and it probably doesn't have just one explanation. The problem could be caused by an unlucky combination of a certain pesticide and a certain virus working as accomplices.

The search for an explanation has gotten easier, scientists say. For example, new laboratory tools now allow researchers to search directly for the genetic footprints of viruses in tumors, and look for the vestiges of pesticide exposure in a person's blood.

"We have an increasingly lengthy list of associations," he said. "It's quite clear that one thing isn't the cause."

ILLUSTRATION(S) 1. Illustrations of how cancer can devastate various part of the bodies of both men and women.

2. CHART: THE PRIMARY SUSPECTS ARE: Chemicals, Viruses and Diet.
© 1999 The Dallas Morning News All Rights Reserved - Laura Beil / Public Health Writer of The Dallas Morning News, TROUBLING TREND.

Well Lyndon, it would be interesting to find out if organic red meat and/or foods caused the same health results.  We really do not need to POISON our food, air, water and planet with your "registered" POISONS, when there are far more effective, less expensive and safer alternatives.  Lyndon, it has been discovered that your "registered" pesticide POISONS have been found in the amniotic fluids in entire groupings of pregnant, middle-class women during their second trimester.  Thereby ensuring that their unborn babies are literally bathing in your "registered" pesticide POISONS during their development. That is how my son died.  Lyndon - How does any of this make you feel?  When will it be "legal" (in your opinion) to wash your can in California with unregistered soap and water, and in so doing,  to"legally" kill the flies and maggots enclosed therein?

Respectfully, Stephen L. Tvedten.
 

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