Cancer Research Distant metastases are mostly derived directly from cancerous tumors

Dangerous distant metastases are often "daughters" of cancerous ulcers
Researchers have found that distant metastases are often "daughters" of the original tumors. So far, the science had assumed that they are primarily from secondary tumors in the lymph nodes. The new findings may explain why lymph node removal often does not prolong life expectancy.

Improvement in the treatment of cancer patients
According to a new study, dangerous distant metastases, for example in the lungs or liver, are mostly daughters of the original tumors. So far, it was assumed that they arise mainly from secondary tumors in the lymph nodes. The new findings may lead to "improvements in the clinical management of lymph node metastasis," study coordinator Kamila Naxerova of the Massachusetts General Hospital (MGH) in Boston, USA, said in a statement.

Cancer patients often remove not only the primary tumor but also distant metastases. However, such interventions do not significantly extend life expectancy. A research team has now discovered why this is so. (Image: edwardolive / fotolia.com)

Operative removal only sometimes prevents distant metastasis
"If cancer has metastasized, many affected patients expect that their disease can be stopped, but a complete cure is often no longer possible," write the experts of the German Cancer Research Center (DKFZ) on the portal "Cancer Information Service".

If only adjacent lymph nodes are affected, they may be selectively surgically removed. According to DKFZ, this also applies to individual distant metastases, depending on the situation.

However, surgical removal only sometimes prevents distant metastases. In the current study published in the journal "Science", the researchers have now discovered why this is so.

Common hypothesis invalidated
MGH researchers, together with colleagues from other research institutes, investigated the relationships between colorectal carcinoma tumors (primary tumors), metastases in the lymph nodes and distant metastases in other body organs by genome sequencing and pedigree analyzes.

Also participating in the study were the Austrians Johannes Reiter and Martin Nowak, both of whom are researching biomathematics at Harvard University in Cambridge (USA).

As Reiter explained to the news agency APA, the most common hypothesis among the medical profession was that a primary tumor first forms lymphoid metastases and later sends them out distant metastases.

For this reason, in cancer patients often not only the primary tumor, but also nearby lymph nodes were surgically removed.

"Several studies have shown that such interventions do not significantly extend life expectancy," he said.

Distant metastases are mostly from the original tumor
The study now showed why this is so. According to the data, the distant metastases in two thirds of the patients were not derived from lymph node tumors, but directly from the original tumor.

"This implies that the surgical removal of the lymph nodes can not prevent the distant metastases," the researchers conclude.

They found that lymph node and distant metastases are out of a line in only a third of cases.

This means that the lymph node plants are probably the parents of the distant metastases. It is said that the removal of the lymph nodes could be life-prolonging only in such cases. (Ad)