Let's start with the Wikipedia page on the history of cancer:
The earliest known descriptions of cancer appear in seven papyri, discovered and deciphered late in the 19th century. They provided the first direct knowledge of Egyptian medical practice. Two of them, known as the "Edwin Smith" and "George Ebers" papyri, contain descriptions of cancer written around 1600 B.C., and are believed to date from sources as early as 2500 B.C.
Several Greeks are also credited with knowing about cancer (centuries after the Egyptians, of course), namely, Hippocrates and Celsus. More practical developments continued in Europe from the 16th century onwards, when autopsies revealed more about tumors. This was eventually applied to surgeries removing tumors.
about.com also mentions Hippocrates (who apparently gave the disease its name) and the ancient Egyptians, noting that the first documented case of cancer occurred in 1500 B.C. It also talks about how autopsies eventually revealed how tumors factored in to the development of cancers. Here's the passage about Egypt:
The world's oldest documented case of cancer hails from ancient Egypt, in 1500 b.c. The details were recorded on a papyrus, documenting 8 cases of tumors occurring on the breast. It was treated by cauterization, a method to destroy tissue with a hot instrument called "the fire drill." It was also recorded that there was no treatment for the disease, only palliative treatment.
From here, we find more evidence that the disease can be traced back to Egypt:
Although the word cancer was not used, the oldest description of the disease is from Egypt and dates back to about 3000 BC. It is called the Edwin Smith Papyrus and is a copy of part of an ancient Egyptian textbook on trauma surgery. It describes 8 cases of tumors or ulcers of the breast that were treated by cauterization with a tool called the fire drill. The description adds that there is not treatment for the condition.
Note the similarity between this passage and the previous one, as well as the date of the papyrus listed here. 1500 years older. It is followed by another passage regarding Hippocrates:
The disease was first called cancer by Greek physician Hippocrates (460-370 BC). He is considered the “Father of Medicine.” Hippocrates used the terms carcinos and carcinoma to describe non-ulcer forming and ulcer-forming tumors. In Greek this means a crab. The description was names after the crab because the finger-like spreading projections from a cancer called to mind the shape of a crab.
Finally, we come to another very similar page, with similar text. I suspect some of these sources used each other as sources. Regarding the "any form" part of your recent edit, there's something interesting here:
Some of the earliest evidence of cancer is found among fossilized bone tumors, human mummies in ancient Egypt, and ancient manuscripts. Growths suggestive of the bone cancer called osteosarcoma have been seen in mummies. Bony skull destruction as seen in cancer of the head and neck has been found, too.
Evidence suggests that osteosarcoma was one of the first recorded cancers. However, the first appears to be breast cancer:
Our oldest description of cancer (although the word cancer was not used) was discovered in Egypt and dates back to about 3000 BC. It’s called the Edwin Smith Papyrus and is a copy of part of an ancient Egyptian textbook on trauma surgery. It describes 8 cases of tumors or ulcers of the breast that were removed by cauterization with a tool called the fire drill. The writing says about the disease, “There is no treatment.”
Funny how that's almost exactly how about.com put it. . . That's because it appears the article used this page as a source.