21.   The cancer develops from the trophoblast, the part of an embryo that invades the womb wall and develops into the placenta.

22.   The new wave of optimism overshadowed the fact that no one knows whether the cancers will develop resistance to Gleevec.

23.   The researchers tried to determine how many breast cancers would have developed and how many women would have died if the surgery had not been performed.

24.   The Zimbabwe researchers note that cervical cancer is developing at increasingly younger ages and at a greater rate as the HIV virus damages immunity.

25.   This cancer can develop without any warning signs, which is why it is so important to get regular screenings.

26.   This pattern suggests that an impaired immune system, at least the type that occurs in AIDS, does not allow common cancers to develop.

27.   Vogelstein has shown how colon cancer can develop when a cell loses two similar tumor suppressor genes.

28.   When these cells begin to grow out of control, a cancer develops called a melanoma.

29.   Prostate cancer often develops late in life and can be very slow growing.

30.   But a new study shows that if a new cancer does develop it is five times as likely to be of an aggressive type.