Filtered Cigarettes Blamed for Huge Rise in Type of Lung Cancer

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The study authors focused on information covering more than 307,000 black and white lung cancer patients, 75 percent of whom were 60 or older at the time of their diagnosis. And they focused on six time periods: 1975-1979, 1980-84, 1985-89, 1990-94, 1995-99 and 2000-03.

Statistics on four major types of lung cancer -- adenocarcinoma, squamous cell carcinoma, large cell carcinoma, and small cell carcinoma -- were tallied to reveal how common each disease had been at the six different time periods. The first three cancers fall into the "non-small cell" category of lung disease that accounts for about 85 percent of all lung cancers in the United States, according to the American Cancer Society.

The SEER figures showed that by the years 2000 to 2003, 47 percent of all lung cancers were adenocarcinoma, Strauss and his team observed.

While American Cancer Society numbers currently place adenocarcinoma at 40 percent of all cases, both ACS and SEER data confirm that adenocarcinoma is by far the most prevalent form of lung cancer today --- regardless of race, age and gender.

In 1950, adenocarcinoma constituted just 5 percent of all lung cancer cases, and a diagnosis of the disease was not typically considered to be due to cigarette smoking. Back in the mid-20th century, most lung cancer cases were squamous cell, the researchers said.

But the SEER data illustrate a sharp rise in adenocarcinoma cases beginning in the 1960s. And from the 1975-79 period to the 1995-99 period, adenocarcinoma cases skyrocketed 62 percent. Adenocarcinoma surpassed squamous cell carcinoma as the most common form of lung cancer among women in the 1975-79 period and among men during the 1980-84 period.

Because the SEER database did not collect information on smoking demographics, the researchers said they subsequently sifted through a wide range of additional data covering 50 years of U.S. cigarette production and consumer habits in search of an underlying explanation.

Strauss and his colleagues said they found that the wide-scale adoption of filtered and low-tar cigarettes closely tracked the jump in adenocarcinoma rates.