First, the energy level of radio waves is relatively low. Electromagnetic energy comes in "packages" that are referred to as photons. Photon energy is measured in electron volts (eV), the energy gained by an electron after accelerating over 1 volt. The energy in the photons depends directly on the frequency, and decreases as one moves down the electromagnetic spectrum. X-rays have about 1,000 eV of energy, while the photon energy of radio waves from cellular phone towers is about one millionth of an eV, not enough to alter molecules in the body.
A second issue has to do with wavelength. Radio waves have a wavelength of approximately 1 foot in air, and about 2 inches in body tissue. As a result, RF radiation can only be concentrated to about an inch or two in size. This makes it unlikely that the energy from radio waves could be concentrated on a small bit of tissue, affecting individual cells.
A third issue has to do with the magnitude of exposure. Measurements taken around typical cellular phone towers show ground level power densities well below the recommended limits. Moreover, public exposure near cell phone towers is not significantly different than background levels of RF radiation in urban areas from other sources, such as radio and television broadcast stations.
For these reasons, cell phone antennas or towers are unlikely to cause cancer.