Infection by some common virus -- most likely mononucleosis, but possibly others as well -- may sometimes lead to Hodgkins disease, an often fatal lymph cancer.
Important new evidence that this may be true -- consequently, a strong new boost for the belief that viruses cause or help cause some cancers -- was reported today.
The evidence comes from a study of the lives of 225 Hodgkins disease patients, persons with twice the normal rate of mononucleosis in their youth. The study is described by two Harvard School of Public Health epidemiologists -- students of disease patterns -- in today's New England Journal of Medicine.
Comparing the Hodgkins patients with 447 healthy persons of the same age, Drs. Nancy Gutensohn and Philip Cole found that Hodgkins appeared most often in those from relatively high-income, well-educated families. And the patients when young typically had no or few brothers and sisters and lived in uncrowded dwellings, with small numbers of playmates.
These uneventful-sounding life histories are important, say these scientists, because they are strikingly like those of persons who most often got serious polio.
In both cases, a sanitary, comparatively isolated childhood evidently meant relatively little exposure to infectious agents and therefore little development of natural immunities early in life. Then when exposure does come in late childhood or adolescence, the results are often severe.
In short, Gutensohn and Cole conclude, many "similarities suggest that Hodgkins disease is a rare consequence" of a virus infection, with the probability of the cancer increasing "as age at time of infection increases."
In isolation, this study would not be a powerful case for calling at least some Hodgkins cases a late aftermath of a virus infection. But taken together with several other pieces of evidence, the "unusually thorough" Harvard investigation will spur a new hunt for guilty viruses, Dr. Robert Gallo, National Cancer Institute tumor biologist, predicted yesterday.
Among the evidence:
There is much data that persons who get "mono" have a greater, if still small, chance of having a lymphoma or lymphatic cancer -- Hodgkins or some other form -- and also some forms of leukemia or blood cancer.
It has been firmly established in recent years that mononucleosis itself is called by the Epstein-Barr virus.
It has virtually been established that this same "E-B virus," in conjunction with exposure to malaria, causes Burkitt's lymphoma, a cancer found in tropical Africa.
E-B virus may also be implicated in nasopharyngeal carcinoma, a cancer of solid tissues, therefore a far more common class of cancer, in the Orient.
Gallo has found that patients with certain lymphomas or leukemias tend to have a more than average number of family members with Hodgkins disease. These leukemias or lymphomas involve the body's T cells, that is, lymphocytes or lymph cells whose role is developing cell immunity.
Much work is needed to prove a virus cause of any cancer, said Gallo, author of a New England Journal editorial on the Harvard study.
One thing that should be emphasized, he said, is that any virus-Hodgkins connection is so slow and indirect -- the lag in the study between viral infection and onset of Hodgkins was five years on the average -- that no mononucleosis or Hodgkins patient should be regarded as "any hazard to anyone else."
If Hodgkins disease indeed has a viral origin, there are probably other viruses too that may trigger it. What Gutensohn and Cole have done, he summed up, is "thrown down the gauntlet" to the virologists to pinpoint the viruses that are truly responsible.