The story is old, but it hurts just the same. The biotech sector served up another dish of foul-tasting news, and once again, investors got sick on it.

The Amex Biotech Index was crushed today, losing almost 30 points to close at 336.03. For those without calculators, that's an 8% collapse. The index has now lost 42% of its value since the beginning of the year. From a technical standpoint, the next major level of support is 300. Ouch.

Idec Pharmaceuticals

(IDPH)

put biotech investors in a selling mood from the get-go this morning, after it

warned last night of a slower-than-expected sales ramp for its new cancer drug, Zevalin. That forced analysts to

take down earnings forecasts for this year and next. Idec lost 16.5% to close Tuesday at $32.03.

Idec joins

Biogen

(BGEN)

as two big-cap, profitable biotech firms that are simply not growing as fast as investors had anticipated (Biogen

issued its earnings warning last week.) So, who's next to fall into this shameful group?

Amgen

(AMGN) - Get Report

, if you believe the rumors sweeping across Wall Street trading floors today, which contributed mightily to the selling pressure.

Amgen is set to make a presentation tomorrow at the Goldman Sachs health care conference, currently under way at a resort just north of San Diego. The rumor had Amgen executives taking down sales estimates for the rheumatoid arthritis drug Enbrel, which Amgen is about to acquire when it closes the

Immunex

(IMNX)

merger. Lower Enbrel sales translate into reduced Amgen earnings, natch.

Well, good news. Amgen isn't likely to warn tomorrow, but that doesn't mean its Enbrel forecast -- $1.6 billion in sales for 2003 -- is safe forever. "It's not a question of

if

they take the numbers down, just

when

they do it," said one biotech fund manager.

Amgen closed Tuesday down $3.06, or 7%, to $38.75 per share.

Medimmune

(MEDI)

also contributed to Tuesday's gloom after executives -- speaking at the Goldman Sachs confab -- continue to preach caution about the chances for quick approval of its FluMist vaccine. Growth-hungry biotech investors want Medimmune to get FluMist on the market in time for this winter's flu season. But company executives are managing expectations because there's still a good chance that FluMist isn't ready in time. Medimmune fell $3.19, or 10.5%, to $27.15 Tuesday.

Biogen, Idec, Amgen, Medimmune: Sense a pattern here? One by one, the growth stories for these widely held, profitable biotech stocks are being taken out back for a good whuppin'. And with little confidence in biotech earnings and growth forecasts, it doesn't matter how cheap these stocks get, investors won't be buying anytime soon (a topic TheStreet.com

broached last Friday).

"This is called panic selling," said one experienced biotech fund manager as he looked over Tuesday's carnage. "Technology-oriented investors who jumped into biotech because they thought they were guaranteed 25%

earnings growth are getting out as fast as they can."

The lesson here is pretty simple: Risk-adjust your growth expectations. There's a reason why biotech is considered a high-risk sector. Things go wrong all the time, as investors have seen all too painfully this year.