Pathology Associates Of Lexington, P.A.

The MAI and the MPI Calculations

MAI and MPI have been found to give prognostic odds which might allow decisions in favor of cytotoxic chemotherapy conservatism. Though the MAI ought to correspond to the mitotic component of the 3-parameter scoring assessment comprising the Elston-Ellis (Nottingham) grading of invasive ductal adenocarcinoma of the breast, that mitotic component might well not have been precisely determined according to the MAI criteria published by the Amsterdam pathology group in Human Pathology 22:326-336, 1991 (and I first heard about it at an ASCP CME 4/1995). Patients/clinicians: if the/your pathology report does not contain a specific measurement of the MAI, you have every right to call the department and request that your case be reviewed and the parameter expertly calculated. It is quite time consuming to do so...especially on limited tumor material (such as limited representation on cores). Results on less than, say, a 50% representation of the imaged size of the neoplasm run the risk of under-representation of cellular, more proliferative tumor portions still in the patient. Your pathologist may need the web site information on this page, below, in order to produce the case MAI and MPI. As a last possible resort, your slides could be forwarded to us; and, if we agree to do so, we can calculate the MAI.

MAI:

Tumor area to assess (make it about a 5 x 5 mm. marked area on the slide):
- choose the most cellular area of invasive cancer & count neighboring fields of view (FOV).
- include tumor periphery
- reject areas with much inflammation
- reject areas with necrosis (if unavoidable, count where as little as possible)
- start count at most mitotically active point by H&E survey
The counting:
- 40x objective & 10x eyepiece (& about 1.59 square mm. field¹)
- only fields with 50% or more invasive cells and less than 50% stroma/CIS/benign stuff
- count only unequivocal, definite mitotic figures
- sum the total of mitotic figures in 10 "40x hpf" fields, and this sum is the MAI, expressed as "___mitoses per 10 40x hpfs¹".
Interpretation¹: proliferation parameters are the most powerful prognostic factor in node-negative women age 55 or less, and proliferation is the attack point of conventional chemotherapy. There is less to be gained from chemo vs. complications when the MAI is less than 10 and an advantageous chemo effect when 10 or higher. If IHC for ppH3 is used to label the mitoses, then the ppH3-amplified MAI breakpoint is 13.

MPI:

square root of MAI times (+0.3341)=__________________
tumor size_________cm. x (+0.2342)=__________________
lymph node status*____ x (-0.7654)=__________________
- *node positive case, 1 point
- *node negative case, 2 points
now sum (keep + and - signs correct) the 3: _{______________}

Survival data for [premenopausal] [ in general] as it might impact chemotherapy decisions

References:

Skaland I & Baak JP, et. al., "Phosphohistone H3...", Modern Pathology 20:1307-1315, 2007.

(posted November 2001; latest update 14 November 2009)