By Dr. Richard Steingart, hematologist, Baystate Regional Cancer Program, for the Daily Hampshire Gazette
Today some one million Americans are living with or in remission from various blood cancers. Hematology/oncology is a combined specialty in which doctors are trained in the diagnosis and treatment of various blood diseases and cancers. The field is rapidly evolving with the introduction of new treatment options for those with blood cancers.
Q: Why is the practice of hematology/oncology combined?
A: Hematologists specialize in the study of blood, and oncologists are cancer specialists. While there are academic medical programs in which hematology and oncology are not combined, most combine the subspecialties as three-year fellowships because each subspecialty complements the other.
Hematology includes most blood cancers – such as leukemia, lymphoma and multiple myeloma – as well as benign (non-cancerous) conditions including iron deficiency; hemophilia; sickle cell disease; clotting disorders; bleeding disorders; and problems with white cells, platelets, and red cells.
Many oncologists focus more on “solid” tumors, such as breast, colon, and lung cancers. In addition, there are transplant physicians who specialize in bone marrow transplants who benefit from being trained in both hematology and oncology. What an individual doctor does depends both on his or her training and the size of the practice the individual works in.
Q: What is the prognosis for blood cancer patients?
A: Great strides have been made in treating blood cancers – lymphoma, both Hodgkin’s and non-Hodgkin’s lymphoma, as well as multiple myeloma, and acute and chronic leukemia.
For example, Hodgkin’s disease in young people is a highly curable disorder. Acute leukemia in children is highly curable as well. Multiple myeloma, in many patients, has become more of a chronic disease with survival of many years.
Newer therapies for chronic lymphocytic leukemia have shown good results in the last several years and chronic myelogenous leukemia, which often led to death in three years, is now for many a chronic disorder, as a result of newer medications called tyrosine kinase inhibitors, which target a specific part of the cancer cell machinery.
Q. What are the most promising developments in treatment?
A: The major advances in blood cancers lie in the field of immune therapy and new biologics. These are medicines, but very different from the traditional “cytotoxic” chemotherapy drugs that have been used for the past 50 years.
Multiple myeloma is now treated with medicines like proteasome inhibitors, which preserve proteins that allow or encourage cancer cells to die, and IMids, which can block tumor blood vessel formation and enhance the immune control of cancer.
These newer classes of drugs have dramatically changed the prognosis for multiple myeloma. People once died of this disease in 3 years or less; now 25-30% of these patients live well over 10 years.
Tyrosine kinase inhibitors (TKIs), which block the growth of cancer cells, have been a major breakthrough particularly for chronic myelogenous leukemia (CML). One TKI, called imatinib, changed CML to a disease with very long survival. In the early 1910s, only 30% of patients lived more than 5 years; now over 90% do so, and many much longer.
In addition, many of these newer drugs are taken orally, not intravenously, so there is greater convenience for patients.
Q. Is there a difference between genetic and genomic testing?
A. Genetic and genomic testing are phrases often used interchangeably – but there is a difference. Genomics usually refers to testing the gene makeup of the cancer itself, while genetics provides information on your individual normal cells and can help estimate your risk for getting cancer.
Q: What role does genomic testing play in the treatment of blood cancers today?
A. Defining certain gene abnormalities, or mutations, specific to certain cancers, allows more targeted therapies to be developed to treat these cancers.
In addition to the CML story, Bruton’s tyrosine kinase inhibitor has made an impact in chronic lymphocytic leukemia (CLL), which has been a stagnant field for many years.
Immune therapies, including rituximab, improved treatment for B-cell non-Hodgkin’s lymphomas, resulting again in better cancer control and longer survival. Sometimes, if the patient relapses and the disease returns, it can be effectively treated with very high doses of chemotherapy and stem cell transplants.
Hairy cell leukemia, a rare form of chronic leukemia, can be treated with a five-day regimen of medication and the disease usually goes into remission for many years. Many feel that this previously lethal disease can often be cured.
Another success is when less toxic treatments can be effective. For example, with acute promyelocytic leukemia, we no longer use the older cytotoxic drugs, but a newer regimen – a combination of arsenic in medicinal doses and all-trans-retinoic acid, an agent derived from a Chinese yew tree – has been able to push the cells to maturation and cure this disease in most individuals.
Unfortunately, certain leukemias are still hard to treat, such as acute myelogenous leukemia in all ages.
The promise in the future clearly rests in research and clinical trials worldwide. Treatments directed by genomic testing and use of targeted immune therapy have made a great difference for some of the diseases mentioned above. The field of malignant hematology is evolving into greater use of targeted immune therapies with potential for very long term disease control rather than standard toxic non-curative chemotherapy.