1.   Follow-up radiation is designed to kill any remaining microscopic cancer cells that may have spread outside the tumor itself.

2.   It has been postulated that vitamin D, which appears to inhibit the growth of tumors, somehow prevents microscopic prostate cancer from progressing.

3.   Apart from vaccines, the work has guided attempts to use the immune system to hunt down and destroy microscopic cancers that have escaped from tumors.

4.   Apart from vaccines, the work has guided attempts to use the immune system to hunt down and destroy microscopic cancer cells that have escaped from tumors.

5.   But if microscopic cancer has reached one or more of the lymph nodes, treatment is more complicated and less likely to cure the cancer, melanoma experts say.

6.   They discovered the microscopic cancer in a subsequent examination.