A new study of over 3,000 human skeletons in a Croatian archaeological collection suggests that cancer is more common today than at any point in humankind's history, the report's authors say. A team of Croatian archaeologists and medics studied ancient human remains dating from 5,300 B.C. to the mid-19th century. The bones, which came from 21 archaeological sites scattered around the eastern European country, are stored at the Skeletal Collection of the Croatian Academy of Sciences and Arts in Zagreb.

Seeking a snapshot of historic human cancer rates over seven millennia, a team of archaeologists and medics examined 3,160 skeletons in a collection at the Croatian Academy of Sciences and Arts. Above, a femur, or thigh bone, shows signs of a benign tumor around the joint.

Photograph courtesy Mario Slaus

Examining the ancient skeletons, researchers found scant evidence of the telltale imprints that some cancers leave.

"While cancer is the number one or two killer in most developed countries today, it was very rare in antiquity," said Mario Slaus, who led the study. Slaus is an anthropologist with the department of archaeology at the Croatian Academy of Sciences and Arts.

"Archaeological populations had little to fear from cancer," he said. "Other infectious diseases where significantly more likely to result in death or affect their quality of life."

Slaus and his colleague presented their study's findings at a meeting of the European Association of Cancer Research in Innsbruck, Austria, earlier this month.

The researchers argue that cancer is more common today because people now have much longer life spans than they did just a few centuries ago. In Croatia, for example, the current average life expectancy is around 74 years. But the average age of death found in the archaeological remains that researchers studied was just 36 years.

Longer human life spans enable slow-developing cancers to appear.

Boney Tumors

The cancer rate in both the developed and developing world continues to increase year by year.

Most cancers are restricted to organs and other soft tissues, but several types leave evidence in the skeleton. While primary tumors of bone, which develop initially in the bone itself, are rare today, secondary metastatic bone tumors are relatively common.

These secondary bone tumors occur when cancers in other soft tissues migrate and form tumors, or metastasize, in the skeleton. They are often found in people who develop cancer later in life.

Both primary and secondary metastatic bone cancer are recognizable as malformations that can be spotted in skeletal remains.

Slaus and his colleagues used this knowledge during their quest to understand the prevalence of cancer through seven millennia of Croatian human history. The team analyzed the bones of 3,160 people held in the Skeletal Collection of the Croatian Academy of Sciences and Arts for both types of tumor.

When researchers ran across something that looked like an unusual growth or scarring in a skeleton, they examined the bones more closely with x-rays and CTscans.

What the scientists found was much the same as has been demonstrated in other archaeological remains: The incidence of cancer was very low. This was particularly true for metastatic bone cancers, the type common in older cancer victims today.

Leprosy More Common

The researchers found benign tumors in four skeletal remains. Tumors were found on the femurs, or thigh bones, of a teenager from a fourth-century necropolis in the town of Mursa, a former Roman colony.

Evidence of a benign tumor was also discovered in the bones of a three- to four-year-old child unearthed in a medieval cemetery near Zagreb.

Another tumor was found in the femur of the remains of man in his 40s found in an 11th-century cemetery in the town of Lobor.

Researchers also discovered tumor signs in the skull of a 50- to 60-year-old man whose remains date to the third or fourth century B.C. and were found on the island of Vis, in the Adriatic Sea.

"The low frequency of [cancer] in the Croatian Skeletal Collection is characteristic for archaeological material," Slaus said. He believes the most likely explanation for the total lack of secondary metastatic bone tumors is that the mean age of death of the specimens is 36 years of age.

While cancer evidence was rare in the remains researchers examined, signs of other diseases, such as syphilis, tuberculosis, and leprosy—which damage bone as well as soft tissue—were much more common.

Slaus notes that cancer would have been as unusual and strange in historical societies as leprosy would seem to us today.

"Star of the Show"

This "fascinating" collection of Croatian skeletons "should prove a valuable resource for other studies," Bruce Rothschild commented. An expert on studying disease in ancient bones, Rothschild is a skeletal pathologist at the Northeastern Ohio Universities College of Medicine in Rootstown. "The authors have a tremendous opportunity with the collection they describe," he said.

Rothschild said that in the roughly 30,000 skeletons from archaeological sites he has examined, cancer—particularly the secondary metastatic form—has also been extremely rare. The pathologist cautions, however, that many metastatic cancers might not cause obvious malformation in the bone and would initially require x-raying to detect.

Speaking of his study, Slaus said, "The bone collection is the real star of the show." Since his study was completed, the number of skeletons has already increased to more than 4,000. The resource continues to grow.

The remains are now being used to study the frequency and distribution of other afflictions and premature deaths, from arthritis and dental disease to fractures and even possible murders.

Slaus said, "Taken together, all of these data helped to corroborate or disprove various archaeological or historic theories and also provide important data not available through other sources."

The unique skeleton collection is now helping to paint an extraordinarily detailed picture of eastern European life and health throughout the ages.