Is left colon cancer more common than right? (COMLEX)

[83462]

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Today I got a question asking for the Chapman's point associated with a patient "passing bright red blood per rectum for the last week" and changes to her stooling habit with rectal tenesmus (feeling of constantly needing to pass stools).

Two of the choices were
-On the R lateral thigh
-On the L lateral thigh*

The answer was on the Left lateral thigh (colon cancer) as "patients without predisposing conditions... left sided disease is more common than right."

Does anyone understand why? Left sided in regards to which diseases?

The correct response rate was pretty high on this one so I'm sure it's a pretty commonly understood pathology. Is it just that the decending colon would be more likely to give you red blood? Looking back, that would have been a good way of knowing that it is left sided. I think.

 

[Nukeleic]

Patients with L sided colon cancer are likely to have s/sx consistent with inability to pass bowel movements and small fecal caliber. R sided colon cancer on the other hand has few presenting symptoms due to the amount of space available for the cancer to grow unimpeded by visceral structures, i.e. there is room for distention. R sided cancer is more likely due to HNPCC, at least as far as boards are concerned. Page 352 and 353 of Goljan has good summary and explanation.

 

[Jamiu22]

Patients with L sided colon cancer are likely to have s/sx consistent with inability to pass bowel movements and small fecal caliber. R sided colon cancer on the other hand has few presenting symptoms due to the amount of space available for the cancer to grow unimpeded by visceral structures, i.e. there is room for distention. R sided cancer is more likely due to HNPCC, at least as far as boards are concerned. Page 352 and 353 of Goljan has good summary and explanation.

Another good pearl: Left side obstructs, right side bleeds!

 

[83462]

Ok, but wait... maybe its just late in the day and i'm low on sleep but doesn't the right sided bleeding contradict with the answer that they gave? Does anyone else see a conflict?

 

[Jamiu22]

Ok, but wait... maybe its just late in the day and i'm low on sleep but doesn't the right sided bleeding contradict with the answer that they gave? Does anyone else see a conflict?

From: http://quizlet.com/4359407/si-and-li-cancer-flash-cards/

Very important to distinguish because the prognosis is totally different

Left side obstruct, right side bleeds.

Why:

1) left side has smaller diameter so when cancer develops it goes out and decides there is not enough room so it goes around and you get annular(napkin ring) and obstruction-->alteration in bowel habits

2)Right has bigger diameter and has greater chance of going out and forming polyp, sits in stool and bleeds --> iron deficiency

 

[MLT2MT2DO]

From: http://quizlet.com/4359407/si-and-li-cancer-flash-cards/

I've really never heard this, I'd be interested in a legitimate source. Especially since diverticuli are almost always seen on the left and this is the most likely cause to cause blood in the feces

 

[Jamiu22]

I've really never heard this, I'd be interested in a legitimate source. Especially since diverticuli are almost always seen on the left and this is the most likely cause to cause blood in the feces

No you are are right about diverticula disease being left side (and can predispose to bleeds), so is angiodysplasia... was adding on to the previeous poster about differentiating left vs right colorectal cancers...

To the OP... sorry, but the question was not too specific (or it was simply a poorly written question) - so it's hard to give you a definite answer... did the symptoms seem to lead you towards colon cancer?

 

[MLT2MT2DO]

No you are are right about diverticula disease being left side (and can predispose to bleeds), so is angiodysplasia... was adding on to the previeous poster about differentiating left vs right colorectal cancers...

To the OP... sorry, but the question was not too specific (or it was simply a poorly written question) - so it's hard to give you a definite answer... did the symptoms seem to lead you towards colon cancer?

It's a comlex bank, the questions are usually poorly written to reflect how they are written on our actual board.

OP: I remember that question and went with left sided because of the "bright red blood". I assumed if it was right at very least it would have been oxidized and much darker by the time it is passed.

 

[beatsbydre]

more happens on left:

http://www.cancerresearchuk.org/can...ncidence/uk-bowel-cancer-incidence-statistics

 

[83462]

It's a comlex bank, the questions are usually poorly written to reflect how they are written on our actual board.

OP: I remember that question and went with left sided because of the "bright red blood". I assumed if it was right at very least it would have been oxidized and much darker by the time it is passed.

yah. the bright red blood would be a great way to come up with a reasonable answer for this question.

 

[coolforschool]

Today I got a question asking for the Chapman's point associated with a patient "passing bright red blood per rectum for the last week" and changes to her stooling habit with rectal tenesmus (feeling of constantly needing to pass stools).

Two of the choices were
-On the R lateral thigh
-On the L lateral thigh*

The answer was on the Left lateral thigh (colon cancer) as "patients without predisposing conditions... left sided disease is more common than right."

Does anyone understand why? Left sided in regards to which diseases?

The correct response rate was pretty high on this one so I'm sure it's a pretty commonly understood pathology. Is it just that the decending colon would be more likely to give you red blood? Looking back, that would have been a good way of knowing that it is left sided. I think.

Just tying up loose ends here. Per UW:

"The location of colon adenocarcinomas influences clinical manifestations. Left-sided colon cancers tend to infiltrate the intestinal wall and encircle the lumen; hence, they present with symptoms of partial intestinal obstruction. Change in the stool caliber, constipation, cramping abdominal pain, abdominal distention, nausea and vomiting occur.

Right-sided colon cancers usually grow as exophytic masses. Patients do not generally develop intestinal obstruction because the right-sided colon has a larger caliber on the left. Right-sided colon cancers usually present with manifestations of iron deficiency anemia (fatigue and pallor) due to the ongoing blood loss. Non-specific symptoms such as anorexia, malaise, and weight loss occur."

 

[SLC]

I'd always been taught that if a left sided colon cancer was going to bleed it would be bright red, and if a right sided colon cancer was going to bleed, it would be darker.

Blood doesn't spend hours+ getting from the right colon to expulsion with the feces and manage to come out bright red...I always learned "the brighter the blood, the closer to the rectum.

Right: Occult bleeding or blood mixes with stool (dark or marroon colored stool).

Left: Frank red bleeding. (not that there always will be blood, but if there is, it will be brighter).

Throw that in with the fact that the patient has been experiencing tenesmus and I think this is a slam dunk question. (if only I knew my chapman points).

BTW: Is nobody going to comment on why we're even being asked about this chapman's point garbage?

 

[MLT2MT2DO]

BTW: Is nobody going to comment on why we're even being asked about this chapman's point garbage?

Don't be ridiculous. How else are you going to diagnose colon cancer? It's not like this is the future and we have cameras and the ability to biopsy said lesions.

I'm guessing if someone has pneumonia you'd rather give them antibiotics instead of efflurage, also? Ludicrous!

 

[SLC]

Don't be ridiculous. How else are you going to diagnose colon cancer? It's not like this is the future and we have cameras and the ability to biopsy said lesions.

I'm guessing if someone has pneumonia you'd rather give them antibiotics instead of efflurage, also? Ludicrous!

Effleurage? That's a novice move, everyone knows that a little thoracic duct-pedal pump action will cure just about anything...