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Introduction ⬇

Cancer cells have abnormal amounts of nuclear DNA. The higher the grade of tumor cells, the more likely the DNA content will be abnormal. The determination of tumor ploidy (the number of chromosome sets in a cell; i.e., diploid, two sets; triploid, three sets) is made by various methods: Flow cytometry, histograms, and image analysis divide cells into triploid/diploid (slowly replicating cells) or aneuploid (rapidly replicating cells).

ERs and PRs in the cells of breast and endometrial cancer tissues are measured to determine whether the cancer is likely to respond to endocrine therapy or to removal of the ovaries. DNA ploidy analysis measures cell turnover in a specimen identified as cancer and predicts progress, shorter survival, and relapse in some patients with cancer of the bladder, breast, colon, endometrial, prostate, kidney, or thyroid. The predictive value is greater for breast, prostate, and colon. The DNA index is the measure of the DNA content of tumor cells compared to normal cells.

Procedure ⬆ ⬇

  1. Obtain a fresh tissue specimen by biopsy, keep on ice, and deliver immediately to the histology laboratory.

  2. Examine a 1-g specimen of quickly frozen tumor for saturation and express in a Scatchard plot. Do not place the specimen in formalin. Some laboratories can perform estrogen receptor assay/progesterone receptor assay studies on paraffin-embedded tissue. Check with your laboratory for specific instructions.

  3. Classify specimens for DNA ploidy on the basis of the percentage of epithelial cells that contain diploid (2n) DNA content and nondiploid (aneuploid) DNA content. DNA content is calculated as the DI.

  4. See Chapter 1 guidelines for intratest care.

Clinical Implications ⬆ ⬇

  1. A positive test for ER occurs at levels of 10 fmol/mg (10 nmol/kg) and for PR binding at levels of 10 fmol/mg (10 nmol/kg). The frequency of positive ER and PR is higher in postmenopausal women.

  2. Approximately 50% of ER-positive tumors respond to antiestrogen therapy, and 60%–70% respond in patients with both ER- and PR-positive tumors.

  3. ER-negative tumors rarely respond to antiestrogen therapy.

  4. The finding of positive progesterone increases the predictive value of selecting patients for hormonal therapy.

  5. The presence of aneuploid peaks in the replicative activity of neoplastic cells may be prognostically significant, independent of tumor grade and stage.

  6. The greater the amount of cells in S phase (DNA synthesis) of the cell cycle, the more aggressive the tumor.

  7. Positive aneuploidy points to a favorable prognosis in some conditions, such as acute lymphoblastic lymphoma and neuroblastoma and perhaps transitional cell bladder cancer.

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain purpose and procedure of testing. Obtain appropriate clinical history so that this information can be provided with the specimen.

  2. Be aware that positive ER and PR means that antiestrogen drug therapy may be beneficial.

  3. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Clinical Alert

Contraindications include:

  1. An uncooperative patient

  2. Bleeding diathesis tendency—anticoagulant therapy

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. Counsel the patient appropriately about possible treatment.

  2. Follow Chapter 1 guidelines for safe, effective, informed posttest care.

Reference Values ⬆

Normal

ER: negative

PR: negative

DI: 0.9–1.0 is normal DNA ploidy (content) or the diploid state.

An interpretive histogram by flow cytometry classifies the stained nucleic as DNA diploid, DNA aneuploid, DNA tetraploid, or DNA uninterpretable.