February 9, 2007 -- Cancer will affect 1 in 2 men and 1 in 3 women in the United States, and the number of new cases of cancer is set to nearly double by the year 2050. Both predictions are based on statistics collected by the Surveillance Epidemiology and End Results (SEER) program at the National Cancer Institute (NCI).

The predictions come from an analysis of data collected from 1975 to 2003, summarized in a paper in the January issue of the Oncologist.

"NCI's SEER program is a finger on the pulse of cancer diagnosis, treatment, and outcome in the United States," says Bruce Chabner, MD, editor-in-chief of the Oncologist. "By looking how frequently cancer occurs in Americans and how long they live after the diagnosis, the SEER program can tell public health officials where progress has occurred as well as where there is a need to redouble our efforts."

As of January 2003, there were an estimated 10.5 million people in the United States who had received a diagnosis of cancer (the figure includes those who are cancer-free). More than half, 5.8 million, were women.

The number of new cases of cancer is expected to nearly double, from 1.36 million in 2000 to almost 3 million in 2050, due to aging and the growing US population. Much of this increase in the number of new cancers will be in the 65-to-84-year age group, and this will reach a peak at 2030, as the baby-boomer generation ages, the NCI researchers comment.

This future increase in new cases of cancer is similar to that predicted in Europe, where it is also being attributed to the aging of the population, as reported from the Annals of Oncology earlier this week by Medscape.



Trends of Cancer Incidence

The NCI researchers also highlight several trends in cancer incidence that have emerged during the 1975-2003 period.

In women, the age-adjusted incidence rates for cancers at all sites have continued to rise from 1979 to 2003, although the rate of increase diminished after 1987. Cancers on the increase in women include leukemia, lung cancer, melanoma, non-Hodgkin's lymphoma, and thyroid cancer, which began to increase sharply during the early 1980s. The increase in thyroid cancer in women is "particularly notable," the researchers comment; the incidence is double that in men and is due partially to occurrence after diagnosis of other primary cancers.

Ovarian cancer began to decline in 1985 and has continued to decline to 2003, and the incidence of breast cancer has shown a "recent stabilization and possible decline," the researchers note. This trend was discussed at the San Antonio Breast Cancer meeting in December 2006 and was reported at that time by Medscape. In this paper, the NCI researchers say a detailed examination of breast cancer incidence shows stable rates in the most recent time period (2001-2003), preceded by a deceleration in the rate of increase since about 1987. Factors that may explain this possible decline include the reduction in hormone therapy among postmenopausal women following the 2002 publication of the Women's Health Initiative and population effects of screening practices with mammography.

In men, the age-adjusted incidence rates for cancer at all sites increased dramatically until 1992, fell sharply during the next few years, and have been stable since 1995. Cancers on the increase in men include those of the kidney and renal pelvis, leukemia, and melanoma (although this began to stabilize in 2001), while decreases were seen for cancer of the oral cavity, pharynx, and lung. The trend for prostate cancer seemed to fluctuate, with a sharp decline between 1992 and 1995, followed by a modest increase in the most recent segment from 1995 to 2003.



Blacks Had Highest Incidence and Mortality

Blacks had the highest incidence rates and also the highest death rates for men and women for all sites combined. For example, prostate cancer had an incidence among black men of 258.3 per 100,000 compared with 163.4 per 100,000 for white men.

In general, black patients have a lower relative survival, independent of cancer site and stage at diagnosis, the NCI researchers comment. This health disparity may be partially due to variations in the prevalence of risk factors, the use of screening tests, access to healthcare services, and/or social and demographic factors, they suggest.

Oncologist.2007;12:20-37.