Provides that any: (i) melanoma; or (ii) condition of cancer affecting lymphatic, digestive, hematological, urinary, prostate, neurological, breast and reproductive systems, resulting in total or partial disability or death to a volunteer firefighter, who successfully passed a physical examination on entry into firefighter service, which examination failed to reveal any evidence of such a melanoma or condition, shall be presumptive evidence that it was incurred in the performance and discharge of duty unless the contrary be proven by competent evidence. |