Thousands more lung cancer patients each year could be offered surgery or other aggressive therapy under a new system that classifies many tumours as more treatable than in the past.
It is the first big overhaul of a decades-old method used to predict survival and help determine whether a lung cancer patient will have surgery, chemotherapy or be treated at all.
The new guidance is to be presented at a conference of lung cancer specialists in Seoul, South Korea, that starts Saturday. It is expected to be adopted by policy-making groups in the next year.
Lung cancer is the world's top cancer killer, claiming 1.3 million lives each year. In the United States, 213,380 new cases and 160,390 deaths from the disease are expected this year.
Nearly 60 per cent of people die within one year of diagnosis, and nearly 75 per cent die within two years, American Cancer Society statistics show.
In 2007, an estimated 23,300 Canadians will be diagnosed with lung cancer and 19,900 will die of it, the Canadian Cancer Society says on its website.
In treating lung cancer, doctors use a formula called tumour staging. It is based on a tumour's size, how far it has spread and other factors to predict a patient's survival odds and to guide treatment.
The current system was developed from about 5,000 tumour samples from University of Texas M.D. Anderson Cancer Center in Houston decades ago - before improved scanning technology was available to evaluate a cancer's spread.
The new plan is based on 100,000 tumour samples from around the world including Asia, where lung cancer rates are projected to climb because of trends in smoking, unhealthy lifestyles and aging populations.
It keeps four broad groupings but sorts people more precisely based on refined understanding of tumour characteristics.
The result: "There will clearly be shifting of patients from categories not operable to operable" - as many as 10,000 a year in the United States, said Dr. David Johnson, a lung cancer specialist at Vanderbilt University in Nashville, Tenn. He reviewed the plan, which was partly published in a medical journal recently.
The stage of the tumour at diagnosis is the best predictor of survival. Only 20 per cent of cases are diagnosed in Stages 1 or 2, when tumours are small and confined to a lung, Johnson said. About 30 per cent to 40 per cent are found in Stage 4, after they have widely spread. The rest are in the middle.
Five-year survival rates are 47 per cent for Stage 1 and 26 per cent for Stage 2, but only eight per cent for Stage 3, and two per cent for Stage 4, according to the American College of Surgeons.
Most lung cancers are the type called "non-small cell," which is covered by the new staging system. The system was developed by the International Association for the Study of Lung Cancer, a group of lung cancer specialists from around the world.
Dr. Peter Goldstraw, a surgeon at the Royal Brompton Hospital in London, led the project, and Canadian scientists independently validated the recommended changes by comparing survival across geographic regions.
Among the changes: creating more sub-stages for tumour size, reassigning some large tumours to a more advanced stage, reclassifying tumours that have spread into the fluid surrounding the lung, and recognizing that spread to certain lymph nodes is more dangerous than its spread to others.
"By changing some of these groupings, some patients will get moved to an earlier stage of disease for which we tend to be more aggressive" in treatment, said Dr. Joan Schiller, a lung cancer specialist at the University of Texas Southwestern Medical Center in Dallas.
"Before, a patient may have only been offered chemotherapy. They may now be offered chemotherapy and radiation," or more intense radiation, she said.
Conversely, some people thought to have earlier-stage tumours now will be grouped with those whose tumours have widely spread, and discouraged from undergoing therapies that have little chance of helping them.
"In some cases, patients were getting inappropriately aggressive treatment," Schiller said.
Some people with very small tumours may get away with less therapy - taking out just a segment of lung instead of an entire lobe, said Dr. Stephen Swisher, a chest surgeon at M.D. Anderson.
The impact of the changes in Europe and Japan is unclear because doctors in those countries tend to remove whole lungs rather than lobes to treat lung cancer, Johnson noted.
Doctors hope that ultimately survival will improve, but that won't happen "unless we get patients into the right hands" and they get correct treatment, Johnson said.
Revising the staging system also will do little good if doctors don't do the right tests to properly stage a tumour, said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society.
Staging for lung and other types of cancer should become even more precise in the near future as biomarkers and gene tests are developed to better sort patients, he added.
