Non-Hodgkin's lymphoma, the disease that killed Jacqueline Kennedy Onassis, is an increasingly common form of cancer that often responds to treatment but proves tragically persistent in many cases.
It is a cancer of the lymph system, the network of nodes and vessels that plays a major role in protecting the body against infection.
The cancer usually appears first as a painless swelling of lymph nodes clustered in the neck, armpit or groin, but it can also attack solid organs first.
Early symptoms can also include anemia, weight loss and fever. If not treated early -- and successfully -- the disease can spread through the blood to other parts of the body.
Some 45,000 cases of non-Hodgkin's lymphoma will be diagnosed this year in the United States, according to the American Cancer Society. Meanwhile, the disease will claim about 21,000 lives. For reasons that are not understood, its incidence has increased over 65 percent since the early 1970s.
Noting that survival rates vary widely according to the disease and how early it is caught, the American Cancer society says the overall five-year survival rate has increased from 31 percent to 52 percent in the past three decades.
The figure is somewhat misleading, according to some authorities, because it doesn't reflect some cancers that kill patients many years after a remission.
A much rarer type of lymphoma -- Hodgkin's disease -- has a much brighter prognosis.
Its overall five-year survival rate is about 78 percent, according to the cancer society. The disease, which produces a different type of tumor, usually attacks people in their 20s or 30s.
While certain types of non-Hodgkin's lymphoma afflict young adults and even children, the disease usually attacks people over the age of 50.
Yesterday, the 64-year-old former first lady returned to her apartment in New York after doctors at New York Hospital-Cornell Medical Center said there was nothing further they could do for her.
After her diagnosis in February, she received at least one round of chemotherapy and radiation to her brain after the cancer had spread there.
Non-Hodgkin's lymphoma actually describes a broad family of lymph cancers. Depending on the type, the cancer can spread rapidly or slowly, respond well to therapy or not at all. Some cancers stand a fair-to-excellent chance of a cure, while others can be held at bay but hardly ever cured.
Carefully guarding her privacy, friends and family of Mrs. Onassis released few details of her disease.
But yesterday before Mrs. Onassis died, a spokeswoman said the formerfirst lady suffered from an aggressive form of the disease.
"Aggressive lymphomas can be cured with conventional chemotherapy about a third of the time," said Dr. Richard Ambinder, a medical oncologist at the Johns Hopkins Oncology Center.
A fast-growing type called Burkitt's lymphoma is so aggressive it will recur six months to a year after treatment if it recurs at all.
Other types recur
Other types will recur within a few years of an initially successful treatment. In those cases, doctors start thinking about a "cure" if the disease hasn't resurfaced in five years.
"If it's not controlled [with initial chemotherapy], it is likely that no further chemotherapy will contain the disease," said Dr. Marcia Will, an oncologist with the University of Maryland Cancer Center.
Younger people with aggressive cancers sometimes get bone marrowtransplants if chemotherapy reduces the amount of cancer without eliminating all traces, she said.
"The bone marrow transplant is usually too difficult when someone is over the age of 55 or 60," she said, noting its often severe side effects.
Other cases of non-Hodgkin's lymphoma are called "indolent" because they spread much more slowly.
Patients can harbor such cases for many years and lead an active life, but they are hardly ever cured.
Former Sen. Paul E. Tsongas made a public display of his physical fitness when he battled Bill Clinton for the Presidential nomination two years ago, despite having been diagnosed with a slow-growing non-Hodgkin's lymphoma in 1983 and undergoing an experimental treatment that involved massive doses of chemotherapy, radiation and a bone marrow transplant.
Later that year, he received further chemotherapy when the cancer returned.