Cancer deaths in the U.S. are declining, with four million deaths averted since 1991, according to the American Cancer Society's annual report. Report.
At the same time, the society said the number of new cancer cases will increase from 1.9 million in 2022 to more than two million in 2023. Cancer is the second leading cause of death in the United States after heart disease. Doctors believe it is urgent to understand changes in mortality rates and changes in cancer diagnoses.
Background: Treatment improvements are helping to reduce cancer deaths.
The cancer society highlighted three key factors in reducing cancer deaths: a reduction in smoking, early detection and greatly improved treatments.
One area where treatment has had a significant impact is breast cancer mortality.
In the 1980s and 1990s, metastatic breast cancer was “considered a death sentence,” says University of Texas MD. said Donald Perry, a statistician at the Anderson Cancer Center and an author of the new study. Paper Sylvia K. of Stanford University. Pleuridis and other researchers about breast cancer (several of the article's authors said they received money from companies involved in cancer treatment).
A study published Tuesday in JAMA found that the death rate from breast cancer has dropped from 48 per 100,000 women in 1975 to 27 per 100,000 women in 2019. Almost 30 percent of breast cancer cases include metastatic cancer. Mortality rate.
Breast cancer treatment has improved so much that it has become a bigger factor than screening in saving lives, said Ruth Etzioni, a biostatistician at the Fred Hutchinson Cancer Center.
The drop in death rates among women under 40 who usually don't have regular mammograms, said Dr. Mette Kalakar, professor of medicine at the University of Oslo and Oslo University Hospital, “indicates a substantial effect of treatment,” he said. .
“The biggest untold story in breast cancer is how much treatment has improved,” said Brigham and Women's Hospital cancer epidemiologist Dr. H. Gilbert Welch said. “That's vaguely good news.”
What We Don't Know: New Cancer Causes.
The American Cancer Society has found increases in the incidence of many cancers, including breast, prostate, ovarian, oral cavity, liver (in women but not men), kidney, and midline colon and rectum. Older adults. Melanoma incidence also increased. The numbers are adjusted for changes in population.
The Cancer Society's chief scientific officer, Dr. William Dahut, said that while the overall rate of colon cancer continues to decline, he is concerned about the increase in one group: the under-55s. Among those younger, the society reports, the incidence is now 18.5 per 100,000 and has been increasing 1 percent to 2 percent annually since the mid-1990s, with 30,500 expected to be diagnosed this year.
In the late 1990s, colon cancer was the fourth leading cause of cancer-related deaths in people under the age of 50. It is now the leading cause in men under 50 and the second leading cause in women. Doctors can't say why.
“We don't have a good explanation,” Dr. Dahut said. “We wave a lot. Is it a diet? Obesity? Is it something in context? Is it in utero exposure?
But colon cancer remains a cancer of the elderly — among them, the cancer society says, it's declining by 3 percent a year in people over age 65. Its incidence is now 155.4 per 100,000, and 87,500 people are expected to be diagnosed this year.
Facts to keep in mind: Cancer incidence is difficult to explain.
Cancer researchers say that the more you look for cancer, the more you find. As screening becomes increasingly sensitive, doctors are finding more and more cancers.
This sounds like a good thing – wouldn't it be better to get rid of cancers before they become dangerous? The problem is that sometimes treatment may be unnecessary because not every cancer is life-threatening or undetectable. Some cancers do not spread. Others actually walk away. Others may eventually have a fatal outcome, but one person dies of something else first. But it's impossible to tell harmless cancers from malignant ones, so everyone is treated.
The condition is called overdiagnosis, but no one can say exactly how often it happens. With mammography, Dr. Perry says, overdetection rates range from 0 to 50 percent.
“There is always an increase in events at first glance, but why they occur is because they may be an artefact,” Dr Etzioni said.
That is the challenge facing cancer researchers now.