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Only one in 10 cancer deaths is caused by the primary tumor. The vast majority of cancer mortality is caused by cells breaking away from the main tumor and metastasizing to other parts of the body, such as the brain, bones, or liver.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
There are approximately 3 million unintended pregnancies in the United States each year.
Medications that are definitely not safe to take when breastfeeding include radioactive drugs, antimetabolites, some cancer (chemotherapy) agents, bromocriptine, ergotamine, methotrexate, and cyclosporine.
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).