Blood Cancer Patients and Stem Cell Transplants

A new study shows older blood cancer patients should be able to receive stem cell transplants no matter what age group they are in– 60 to 64, 65 to 69 or 70 to 75. Patients in all three age groups had comparable survival rates, suggesting age played a limited role in how patients tolerate the mini-transplant, a “kinder, gentler” form of allogeneic (donor cell) stem cell transplantation developed at Fred Hutchinson Cancer Research Center.

“Age is no longer a barrier to allogeneic transplant,” Mohamed Sorror, M.D., M.Sc., an assistant member of the Hutchinson Center’s Clinical Research Division was quoted as saying.

The mini-transplant, known in medical circles as nonmyeloablative transplantation, was developed by researchers at the Hutchinson Center for older and medically sicker patients who otherwise could not tolerate the standard, more-toxic, high-dose regimens used to prepare patients for transplantation. Conventional transplants, which are generally not performed on people over age 60 or others who are medically unfit, use high doses of total-body irradiation and potent chemotherapy to eliminate leukemic cells. The intense treatment destroys the blood and immune system and is fatal unless the patient is rescued by infusion of donor bone marrow or stem cells isolated from peripheral blood. The mini-transplant, in contrast, relies on the ability of donor immune cells to target and destroy the cancer – without the need for high-dose chemotherapy and radiation. Instead, low-dose radiation and chemotherapy is used to suppress the immune system rather than destroy it. This helps the body accept the donor stem cells, which then go to work to attack cancer cells – called the graft-vs.-leukemia effect – and rebuild the immune system.

The study involved 372 patients ages 60 to 75 who were enrolled in prospective clinical trials between 1998 and 2008 at 18 collaborating U.S. and European cancer centers known as the “Seattle Consortium.” All patients at these centers were treated with the same regimen, which was developed in Seattle. The patients in the study were treated for acute and chronic leukemia, lymphoma, multiple myeloma, myelodysplastic syndromes (which can progress to acute myeloid leukemia if not treated) and myeloproliferative diseases such as chronic myelogenous leukemia.

“These findings, together with the normal to near-normal performance status of surviving patients, should help allay reluctance in entering older patients with hematologic cancers on nonmyeloablative transplantation protocols. The lack of a matched sibling donor also should no longer be a limitation given that transplants with matched unrelated donor grafts had comparable outcomes,” Sorror was quoted saying.

20 percent of the U.S. population will be 65 or older by 2030, and that increases of up to 77 percent in the number of newly diagnosed blood cancers among this population are expected to occur in the next two decades. Such malignancies are mainly diseases of the elderly. Yet, only 12 percent of patients who were treated with a transplant between 2004 and 2008 in U.S. institutions were over age 60 and a previous study suggested that only 26 percent of patients with acute myeloid leukemia were treated with a transplant, according to results reported by the Center of International Blood and Marrow Transplantation Research.

“These statistics clearly highlight the reluctance of providers in offering allogeneic stem cell transplantation to the elderly. Little is known about the reasons behind the low referral rate of older patients to transplant or how mini-transplant outcomes compare to those of conventional therapies. We are initiating a multicenter study designed to follow patients from the time of diagnosis to answer both questions,” Sorror was quoted saying.

Clearly, there is a hope for older patients to receive a blood cancer treatment with less side effects and with more willing providers to accept older patients for a treatment.

Source: JAMA, published November 2011

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