NEW YORK - Cigarette smoke
can transform normal breast cells into cancerous cells by blocking their normal
ability to repair themselves. Over time this could lead to the development of
breast cancer, scientists from the University of Florida in Gainesville report.
Smoking cigarettes substantially increases a person's risk of developing
heart disease, as well as cancer of the mouth, pharynx, larynx, esophagus,
pancreas, kidney, bladder and uterine cervix. Whether cigarette smoking
increases the risk of breast cancer risk remains controversial.
Studies that have looked at the relationship between tobacco and breast
cancer have found only weak correlations or none at all. Most of these studies,
however, have focused on single chemical components of tobacco.
For their research, the Gainesville team used cigarette smoke condensate or
tar that contains all of the chemicals present in cigarette smoke, 81 of which
have been classified as cancer-causing.
"The use of cigarette smoke condensate...mimics the human smoking situation
more closely," Dr. Satya Narayan told Reuters Health.
Narayan and colleagues found that after treatment with cigarette smoke
condensate normal human breast epithelial cells in culture acquire mutations
characteristic of malignancy. "The concentration of the condensate we used is
much lower than it is present in one cigarette," Narayan pointed out.
The Gainesville research also pinpoints the mechanism by which cigarette
smoke transforms normal breast cells into cancerous cells. Cigarette smoke
"causes DNA damage and at the same time compromises the DNA repair capacity of
the cell, perhaps, leading to mutation and transformation of targeted breast
epithelial cells."
A DNA repair defect in a single cell that cannot be repaired efficiently
before it divides can lead to the genesis of tumors, Narayan said.
When people smoke, they inhale 4,000 different chemicals, which can produce
harmful effects in our body, Narayan said. Since the development of cancer is a
complex phenomenon and requires several gene mutations during its progression,
the defective cell can be present for several years before it acquires
tumorigenic activity, the researcher added.
Therefore, the safest way around this is to stay away from cigarettes. "This
will protect us from the long-term known and unknown causes of cigarette smoke
chemicals on our health," Narayan said.
SOURCE: Oncogene, August 21, 2006.
