Life Span of CML Patients Approaches Usual Limits

Pam Harrison

June 28, 2016

The life expectancy of patients with recently diagnosed chronic myeloid leukemia (CML) is now approaching that of the general population, which is an important message for physicians to convey to newly diagnosed patients, Swedish research suggests.

"Recently diagnosed patients will, on average, lose less than 3 years of life due to their diagnosis of CML, which can be seen as a great success of CML treatment," Hannah Bower, a doctoral candidate in the Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden, told Medscape Medical News.

"We hope this continuous improvement will be maintained," she said.

The study was published online June 20 in the Journal of Clinical Oncology.

For their analysis, the researchers studied 2662 patients who were diagnosed with CML between 1973 and 2013 in Sweden.

As might be expected, the life expectancy of all Swedish residents increased during the 50-year follow-up period.

Similarly, "the life expectancy of the patients with CML steadily increased for all ages between 1973 and 1990," Bower and colleagues note.

Increases in life expectancy differed, depending on the age at which patients were diagnosed and on the interval during which increases in life expectancy occurred.

For example, a large increase in life expectancy was seen for younger patients after 1990.

Patients who were diagnosed with CML at the age of 85 years enjoyed the greatest increase in life expectancy, starting around 2000.

Increases in life expectancy for patients with CML also burgeoned across time. A 55-year-old patient who was diagnosed with CML in 1980, for example, would on average have only 3.5 years left to live, but a 55-year-old patient diagnosed in 2010 would have 27.3 years left to live.

Significant increments in years left to live also were seen among the elderly. For example, an 85-year-old man diagnosed with CML in 1980 would have less than a year left to live, whereas a male patient of the same age could expect to live another 4.1 years if diagnosed with the same malignancy in 2010.

Table. Life Expectancy of the General Population (GP) vs That of CML Patients at Age/Year of Diagnosis (Women Only)

  Age 55 Age 65 Age 75 Age 85
1980        
GP 29.0 19.3 11.3 5.5
CML 4.1 3.2 2.2 1.1
1990        
GP 30.2 20.5 12.0 6.0
CML 6.6 4.5 2.6 1.1
2000        
GP 31.4 21.7 13.0 6.2
CML 17.2 10.6 5.5 2.2
2010        
GP 32.6 22.8 14.0 6.9
CML 29.7 19.8 11.3 5.0

 

Loss of life expectancy decreased during the long follow-up interval. The most dramatic decrease was seen in younger patients after 1990.

The life expectancy of a 55-year-old man diagnosed with CML in 1980 would be expected to be reduced by 20.8 years on average, whereas a male patient of the same age diagnosed in 2010 would be expected to lose only 2.6 years of life.

"For older patients, improvements were still seen, with a more rapid decrease after the 1990s, but not to the same scale as in the younger patients, because older patients have, on average, fewer potential remaining life-years," Bower observes.

Improvement Seen Even Before Imatinib

As Bower and colleagues point out, imatinib (Gleevec, Novartis Pharmaceuticals Corporation), a tyrosine kinase inhibitor (TKI), was first introduced as second-line treatment for CML in Sweden in 2001. It became first-line treatment a year later. Imatinib and similar drugs are widely credited with transforming CML from a life-threatening cancer into a chronic disease.

However, the Swedish data show that at least for the youngest patients diagnosed with CML, improvement in survival started in the mid 1990s, before imatinib was introduced.

Improvements in survival were noted following the introduction of imatinib, but major strides were seen prior to its widespread use.

"This was rather unexpected," Bower noted.

"But we believe this increase [in survival] in younger patients was largely due to allogeneic stem cell transplantation — the treatment of choice in the 1990s — and a more structured approach in treating and monitoring patients with CML."

With the dramatic increase in life expectancy for CML patients, the cost of lifelong TKI therapy could represent a real burden for governments and insurers, as well as patients.

"Most patients with CML will take [a TKI] for life, which, along with the increasing prevalence of CML, has high cost implications," Bower observed.

On the other hand, several "stop" studies have suggested that treatment might be discontinued for patients who achieve complete molecular remission, which would reduce treatment costs, she noted.

"We estimated that patients diagnosed from 2010 will on average have a life expectancy that is within 3 years of the life expectancy of the Swedish general population," Bower affirms.

"Hopefully, this trend will be maintained with the introduction of second- and later-generation TKIs and with better knowledge of which drug to use and when."

Hannah Bower has disclosed no relevant financial relationships. Several coauthors have reported relationships with industry, as detailed in the published article.

J Clin Oncol. Published online June 20, 2016. Full text

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