c-Abl and Arg are activated in human primary melanomas, promote melanoma cell invasion via distinct pathways, and drive metastatic progression.

Despite 35 years of clinical trials, there is little improvement in 1-year survival rates for patients with metastatic melanoma, and the disease is essentially untreatable if not cured surgically. The paucity of chemotherapeutic agents that are effective for treating metastatic melanoma indicates a dire need to develop new therapies. Here, we found a previously unrecognized role for c-Abl and Arg in melanoma progression. We demonstrate that the kinase activities of c-Abl and Arg are elevated in primary melanomas (60%), in a subset of benign nevi (33%) and in some human melanoma cell lines. Using siRNA and pharmacological approaches, we show that c-Abl/Arg activation is functionally relevant because it is requiredfor melanoma cell proliferation, survival and invasion. Significantly, we identify the mechanism by which activated c-Abl promotes melanoma invasion by showing that it transcriptionally upregulates matrix metalloproteinase-1 (MMP-1), and using rescue approaches we demonstrate that c-Abl promotes invasion through a STAT3 → MMP-1 pathway. Additionally, we show that c-Abl and Arg are not merely redundant, as active Arg drives invasion in a STAT3-independent manner, and upregulates MMP-3 and MT1-MMP, in addition to MMP-1. Most importantly, c-Abl and Arg not only promote in vitro processes important for melanoma progression, but also promote metastasis in vivo, as inhibition of c-Abl/Arg kinase activity with the c-Abl/Arg inhibitor, nilotinib, dramatically inhibits metastasis in a mouse model. Taken together, these data identify c-Abl and Arg as critical, novel, drug targets in metastatic melanoma, and indicate that nilotinib may be useful in preventing metastasis in patients with melanomas harboring active c-Abl and Arg.

PDGF-A promoter and enhancer elements provide efficient and selective antineoplastic gene therapy in multiple cancer types.

Development of antineoplastic gene therapies is impaired by a paucity of transcription control elements with efficient, cancer cell-specific activity. We investigated the utility of promoter (AChP) and 5'-distal enhancer (ACE66) elements from the platelet-derived growth factor-A (PDGF-A) gene, which are hyperactive in many human cancers. Efficacy of these elements was tested in multiple tumor cell lines, both in cell culture and as tumor explants in athymic nude mice. Plasmid and viral vectors were constructed with the AChP promoter alone or in fusion with three copies of the ACE66 enhancer for expression of the prototype suicide gene, thymidine kinase (TK). ACE/AChP and AChP cassettes elicited ganciclovir (GCV)-induced cytotoxicity in multiple tumor cell lines. The ACE enhancer element also exhibited synergism with placental and liver-specific promoter elements. An adenovirus containing the AChP-TK cassette produced striking increases in GCV sensitivity in cultured tumor cell lines, as well as GCV-induced regression of U87 MG glioblastoma explants in vivo. TK expression was distributed throughout tumors receiving the therapeutic virus, whereas TdT-mediated dUTP nick end labeling (TUNEL) analysis revealed numerous regions undergoing apoptosis. Vascularization and reticulin fiber networks were less pronounced in virus-GCV-treated tumors, suggesting that both primary and stromal cell types may have been targeted. These studies provide proof-of-principle for utility of the PDGF-A promoter and ACE66 enhancer in antineoplastic gene therapy for a diverse group of human cancers.

The critical role of axillary ultrasound and aspiration biopsy in the management of breast cancer patients with clinically negative axilla.

BACKGROUND: Sonographic evaluation of the axilla can predict node status in a significant proportion of clinically node-negative patients. This review focuses on the value of ultrasound followed by ultrasound-guided cytology in assessing the need for sentinel node mapping and conservative versus complete axillary dissections. DESIGN: Breast primaries from 168 sentinel node candidates were prospectively assessed for clinicopathologic variables associated with increased incidence of axillary metastases. Patients were classified accordingly, and those at a higher risk underwent ultrasound of their axillae, followed by aspiration biopsy if needed. Sentinel node mapping was performed in all low-risk patients, and in high-risk patients with normal axillary ultrasounds or negative cytology. Final axillary status was compared in terms of nodal stage, number of positive nodes, and size of metastasis. RESULTS: 112 patients were at high risk for nodal disease (67%), with a statistically significant lower probability for remaining node-negative and a statistical significantly higher risk for having more than one positive node. All patients with more than three positive nodes were detected by ultrasound-guided cytology. High-risk patients with final positive axillae missed by ultrasound or ultrasound guided cytology had tumor deposits measuring

Primary appendiceal cancer: gynecologic manifestations and treatment options.

OBJECTIVE: To determine the presenting symptoms, gynecologic manifestations, and optimal intraoperative management of women with primary appendiceal cancer. METHODS: A multi-institutional investigation was performed to identify female patients with primary appendiceal cancer who were treated from 1990 to present. RESULTS: Forty-eight women with primary appendiceal cancer were identified from the tumor registries of participating institutions. The most common symptoms were abdominal pain (40%) and bloating (23%), but only 8% experienced rectal bleeding. Serum CEA was elevated (>2.5 U/ml) in 67% of patients, and serum Ca-125 was elevated (>35 U/ml) in 50% of patients. Thirty-one patients (65%) presented with a right adnexal or right lower quadrant mass and were operated on initially by a gynecologic oncologist. Ovarian involvement by metastatic appendiceal cancer was documented in 18 patients (38%). All of these patients underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy, and staging, but only 8 had a right hemicolectomy at the time of initial surgery. Forty-one patients (85%) presented with advanced stage appendiceal cancer (Stage III or IV) and 19 patients (46%) received postoperative chemotherapy, most commonly with a combination of 5-FU/Leukovorin. Following surgery, 22 patients (46%) experienced disease progression or recurrence, and 14 have died of disease. The most common sites of recurrence were abdominal or pelvic peritoneum (18), colon (2), and ovary (2). Patient survival was 70% at 2 years, and 60% at 5 years. CONCLUSION: Women with primary appendiceal cancer frequently present with ovarian metastases, and initial surgical intervention is often performed by a gynecologic oncologist. All patients with mucinous epithelial ovarian cancer should undergo appendectomy at the time of surgical staging. The appendix should be examined intraoperatively, and if appendiceal carcinoma is identified, a right hemicolectomy and appropriate surgical staging should be considered.

The efficacy of adjuvant platinum-based chemotherapy in Stage I uterine papillary serous carcinoma (UPSC).

OBJECTIVE: To determine the efficacy of adjuvant platinum-based chemotherapy in Stage I uterine papillary serous carcinoma (UPSC). METHODS: A retrospective multi-institutional investigation was performed to identify surgically staged patients with Stage I UPSC who were (1) treated after surgery with 3-6 courses of platinum-based chemotherapy without radiation from 1990-2003, and (2) followed for a minimum of 12 months, or until recurrence. RESULTS: Six patients (IA-2, IB-3, IC-1) were treated with carboplatin (AUC 6) or cisplatin (50 mg/m2) alone. One patient recurred to the vagina, was treated with chemo-radiation, and is alive and well at 122 months. One patient recurred to the lung, liver, and brain, and died of disease at 24 months. The remaining 4 patients are alive with no evidence of disease 15-124 months (mean 62 months) after treatment. Two patients (IB-1, IC-1) were treated with cisplatin (50 mg/m2) and cyclophosphamide (1000 mg/m2), and both are alive and well with no evidence of disease 75 and 168 months after treatment. Twenty-one patients (IA-5, IB-13, IC-3) were treated with a combination of carboplatin (AUC 6) and paclitaxel (135 mg/m2-175 mg/m2). One patient recurred to the vagina after 3 cycles of carboplatin/paclitaxel, and was treated with chemo-radiation. She is now without evidence of disease 10 months after treatment. At present, all 21 patients with Stage I UPSC treated following surgical staging with carboplatin/paclitaxel chemotherapy are alive and well with no evidence of disease 10-138 months (mean 41 months) after treatment. CONCLUSION: Combination carboplatin/paclitaxel chemotherapy following surgery is effective in the treatment of Stage I UPSC.

Short-term treatment with novel ribonucleotide reductase inhibitors Trimidox and Didox reverses late-stage murine retrovirus-induced lymphoproliferative disease with less bone marrow toxicity than hydroxyurea.

We evaluated the ability of a short course of treatment with the ribonucleotide reductase (RR) inhibitor hydroxyurea (HU) and two novel RR inhibitors Trimidox (TX) and Didox (DX) to influence late-stage murine retrovirus-induced lymphoproliferative disease. LPBM5 murine leukaemia virus retrovirus-infected mice were treated daily with HU, TX or DX for 4 weeks, beginning 9 weeks post-infection, after development of immunodeficiency and lymphoproliferative disease. Drug effects on disease progression were determined by evaluating spleen weight and histology. Effects on haematopoiesis were determined by measuring peripheral blood indices (white blood cells and haematocrit) and assay of femur cellularity and femoral and splenic content of colony-forming units granulocyte-macrophage (CFU-GM) and burst-forming units-erythroid (BFU-E). HU, TX and DX partially reversed late-stage retrovirus-induced disease, resulting in spleen weights significantly below pre-treatment values. Spleen histology was also improved by RR inhibitor treatment (DX>TX>HU). However, as expected, HU was significantly myelosuppressive, inducing a reduction in peripheral indices associated with depletion of femoral CFU-GM and BFU-E. In contrast, although TX and DX were moderately myelosuppressive, both drugs were significantly better tolerated than HU. In summary, short-term treatment in late-stage murine retroviral disease with HU, TX or DX induced dramatic reversal of disease pathophysiology. However, the novel RR inhibitors TX and DX had more effective activity and significantly less bone marrow toxicity than HU.

Resolution of Ga-67 citrate uptake in the left neck mass of Hodgkin's disease and reversion of double scoliosis of cervical-thoracic and lower lumbar vertebrae.

A 6-yr-old boy underwent a total body Ga-67 citrate imaging study because of a large mass of Hodgkin's lymphoma in the left neck and the left anterior chest wall region. The images showed intense uptake in the left neck extending anteroinferiorly to the left upper chest wall corresponding to the left neck and chest region. In addition, there was mild cervical-upper thoracic scoliosis with convexity to the right and mild scoliosis of the lower lumbar scoliosis with concavity to the left. After three cycles of chemotherapy, in the follow-up Ga-67 citrate total body images seven months after his first Ga-67 citrate imaging, the intense uptake in the left neck and the left upper chest wall had been resolved and the scoliosis of the cervical-thoracic and lower lumbar spine had also been reversed to normal. This case shows that a Ga-67 citrate imaging study is useful for first diagnosis and subsequent monitoring of the therapeutic effects in a follow-up imaging. Also Ga-67 citrate imaging provided evidence that the scoliosis had been reversed.

A soluble transforming growth factor beta type III receptor suppresses tumorigenicity and metastasis of human breast cancer MDA-MB-231 cells.

Transforming growth factor beta (TGF-beta) can promote late stage tumor progression in a number of model systems. In the present study, we have examined whether expression of a truncated soluble extracellular domain of TGF-beta type III receptor (sRIII) in human breast cancer MDA-MB-231 cells can antagonize the tumor-promoting activity of TGF-beta by sequestering active TGF-beta isoforms that are produced by the cancer cells. The secretion of sRIII reduced the amount of active TGF-beta1 and TGF-beta2 in the conditioned medium. This led to a significant reduction of the growth-inhibitory activity of the medium conditioned by sRIII-expressing cells on the growth of mink lung epithelial CCL64 cells in comparison with the medium conditioned by the control cells. The tumor incidence and growth rate of all of the three sRIII-expressing clones studied were significantly lower than those of the control cells in athymic nude mice. Four of five control cell-inoculated mice showed spontaneous metastasis in the lung, whereas none of the sRIII-expressing cell-inoculated mice had any lung metastasis. Thus, our results suggest that the sRIII may be used to antagonize the tumor-promoting activity of TGF-beta.

Handling sentinel lymph node biopsy specimens.A work in progress.

This article reviews the "state of practice" with regard to sentinel lymph node biopsy, a new and evolving technique currently used most commonly for staging of malignant melanoma and adenocarcinoma of the breast. Sentinel lymph node biopsy has the potential to both increase the accuracy of lymph node sampling as a prognostic tool and to decrease the need for unnecessary and morbid extensive lymph node dissection in such patients. The need for close cooperation and planning involving the surgeon and pathologist is stressed, and gross room tissue handling, radiation safety, microscopic examination, and the use of ancillary diagnostic techniques are discussed.

Skin contraction with pulsed CO2 and erbium:YAG laser.

The purpose of this study was to assess the physical response of skin to laser resurfacing in a real-time, quantitative fashion. The study was designed to assess skin contraction from two opposite standpoints. First, change in tension was measured during laser application while samples were held at constant length. Second, change in length of a sample under no tension was measured during laser treatment. These two disparate analyses represent the two possible extremes of the clinical situation in which skin exists under some tension with some laxity to allow for decrease in length. A custom apparatus with digital interface for skin tension measurements was used to produce single sample tracings of change in skin tension with laser treatment. Length change was measured for individual samples by continuous sonomicrometer readings. Individual sample data were then plotted in a time versus tension/length graph. Skin contracts immediately to a peak level and then relaxes to a sustained plateau level for both CO2 and erbium:YAG lasers. Increased contraction was noted when the beam penetrated into the dermis. Greater peak and plateau contraction is observed after the beam has penetrated into the dermis. Skin contraction varies directly with energy for CO2 and erbium:YAG laser. Findings were similar when skin tension was measured with the sample held at constant length and when length change was measured with the sample under no tension. Char left on the skin after a pass with CO2 laser substantially decreases skin contraction. High-density settings with CO2 laser yield pulse stacking, which effectively irradiates the same portion of tissue with char on it. Skin contraction varies inversely with computer pattern density settings for CO2 laser due to this pulse stacking effect. Density has little effect on skin contraction for the erbium:YAG laser because little char is generated. Histologic analysis identified a zone of coagulated dermis that correlates linearly with skin contraction.

Isolation and characterization of a spontaneously transformed malignant mouse mammary epithelial cell line in culture.

A method is described that permits the selection of spontaneously transformed mammary epithelial colonies from an untransformed mouse mammary epithelial cell line, NMuMG, and utilizes a long-term anchorage-independent growth of the transformants on soft agarose. These transformed cells (NMuMG-ST) are shown to be distinguishable from the untransformed cells by morphology, growth characteristics, induced carcinomas when transplanted into nude mice and ability to metastasize. This transformed phenotype displayed focal, multilayer growth and higher saturation density in comparison with the untransformed phenotype. Transplanted tumors as well as metastatic lung tumors in nude mice were adenocarcinomas morphologically similar to typical mammary tumors in humans. This selection procedure of mutant mammary cells from an immortalized cell line derived from normal mammary glands could be very useful to identify the genomic biomarkers in the growth regulation and malignant progression of breast cancer.

Thyroid lymphoma: is there a role for surgery?

The role of surgery in the treatment of Stage I and II non-Hodgkin's thyroid lymphoma (NHTL) is not well defined. At our institution, we have treated seven patients (six women and one man) with NHTL during the past 6 years. Three patients (43%) had a prior history of thyroid disease, usually lymphocytic thyroiditis. Clinical symptoms included a rapidly enlarging neck mass (86%), dysphagia (71%), dyspnea (71%), and hoarseness (71%). Five patients (71%) had hypothyroidism; one patient, hyperthyroidism; and one patient, normal thyroid function. Five patients underwent fine-needle aspiration (FNA) at our institution. In three instances, FNA results were indicative of NHTL; the remaining FNA tests yielded no diagnosis. Surgical procedures were varied: incisional biopsy (n = 4), limited tumor debulking with tracheostomy (n = 2), and thyroidectomy (n = 1). Each of the seven patients was found to have large cell lymphoma. Treatment consisted of combination chemotherapy with consolidative irradiation. All tumors dramatically decreased in size soon after the initiation of therapy. One patient refused radiotherapy. All patients except one are still alive (median follow-up, 24 months). In conclusion, 1) a diagnosis of NHTL, although rare, should be considered when patients have rapidly growing goiters; 2) FNA is a useful first step in diagnosing NHTL; 3) NHTL is exquisitely sensitive to both chemotherapy and radiation; 4) surgical intervention is generally confined to incisional biopsy with occasional limited pretracheal tumor debulking; and 5) when a biopsy is obtained from a patient suspected of having NHTL, immediate processing by the pathologist is recommended so that material can be obtained for special studies as needed.

Single focus of adenocarcinoma in the prostate biopsy specimen is not predictive of the pathologic stage of disease.

OBJECTIVES: To determine whether a very small focus of prostate cancer in a needle biopsy specimen correlates with organ-confined disease or with favorable disease parameters. METHODS: Of 598 needle biopsies of the prostate performed from January 1990 through June 1994, 49 specimens (8.2%) contained a microscopic focus (less than 2 mm in length of the entire biopsy core specimen) of adenocarcinoma. For these 49 patients, the clinical and pathologic features were correlated. RESULTS: Of these 49 patients, 27 (55.1%) underwent either radical prostatectomy, with or without pelvic lymph node dissection (26), or pelvic lymph node dissection alone (1). Seven of these 27 patients (25.9%) had extraprostatic disease: lymph node involvement (1), positive surgical margins (5), or seminal vesicle invasion (1). Ten of the 49 patients (20.4%) underwent radiotherapy, and 12 (24.5%) chose hormonal therapy. The pathologic stage for these 22 patients could not be ascertained. However, despite the limited amount of disease in the biopsy specimen, 2 patients treated with radiotherapy suffered a relapse (mean interval to recurrence, 11.5 months), and 3 patients treated with hormonal therapy (early or delayed) had bony metastasis at the time of diagnosis. Overall, 12 of the 49 patients (24.5%) had unfavorable disease (as defined by extraprostatic disease on pathologic specimen, relapse after radiotherapy, or bony metastasis at the time of diagnosis). CONCLUSIONS: These findings suggest that a microscopic focus of prostatic adenocarcinoma in a needle biopsy specimen, per se, does not predict the pathologic stage or the biologic behavior of a tumor.

Expression of p53 protein in pancreatic adenocarcinoma. Relationship to cigaret smoking.

We studied the expression of p53 gene product in pancreatic adenocarcinomas of the usual ductal type to determine its relationship to cigarette smoking and its usefulness as an independent prognostic indicator. Twenty-six resection specimens of pancreatic adenocarcinoma were examined by immunohistochemistry using an antigen retrieval solution and monoclonal PAb1801 and polyclonal CM1 antibodies on paraffin-embedded material. Specific nuclear p53 expression for both PAb1801 and CM1 was identified in seven cases (27%). In all cases immunoreaction was confined to neoplastic cells. Three of four (75%) tumors from patients who had never smoked showed immunoreaction, whereas only three of 14 (21%) tumors from smokers showed positive staining. Cases with positive staining had shorter mean survival (6.3 mo) than cases that failed to stain (9.8 mo), but the difference was not statistically significant in this small study. There was no statistically significant association between p53 immunoreactivity and other clinicopathologic parameters. Our findings indicate that abnormalities of p53 gene in pancreatic adenocarcinomas may not be directly related to cigarette smoking. Those patients who survived the longest tended to have tumors negative for p53 immunostaining. p53 immunoreaction may be a useful feature in distinguishing adenocarcinoma from chronic pancreatitis in small biopsies.

Etiologies for non-correlating cervical cytologies and biopsies.

To investigate the etiologies for discrepancies between cervicovaginal smear and corresponding cervical biopsy results, 615 patients with cytologic diagnoses of dysplasia or malignancy during 1 year were reviewed. Sixty-nine patients (11%) were identified in which the cytologic and histologic diagnoses differed. Utilizing an algorithm developed for the study, these cases were assigned an etiologic category for discrepancy: colposcopic biopsy or cytologic sampling, cytologic screening, histotechnical processing, histologic or cytologic interpretation. The most common cause for a discrepancy was colposcopic biopsy sampling (36 cases, 51%). There were nine errors (13%) in biopsy interpretation, with seven underdiagnoses and two overdiagnoses. Eight errors (11%) in cytologic interpretation occurred with half of these representing underdiagnoses. The other causes for discrepancy were less common--cytologic sampling (6 cases), histotechnical processing (3 cases), cytologic screening (2 cases), and a combination of factors (5 cases). Use of this algorithm allows laboratories to identify problem areas and design specific corrective protocols to improve diagnostic accuracy and patient care.

Malakoplakia of liver associated with a perforated colonic diverticulum. A case report and review of the literature.

Malakoplakia of the liver is rare, only three cases having been documented in the world literature. Described here is the first case of malakoplakia of the liver as a complication of a perforated colonic diverticulum.

Gleason histologic grading in prostatic carcinoma. Correlation of 18-gauge core biopsy with prostatectomy.

Histologic grading of adenocarcinoma of the prostate gland is a reliable predictor of extension and metastasis. Studies involving correlation of grade between biopsy and prostatectomy specimens have traditionally involved biopsies using a large-bore (14-gauge) cutting needle. However, common practice has shifted to the use of biopsy cores with a smaller caliber (18 gauge). This study was undertaken to determine the degree of correlation of tumor grade between 18-gauge core biopsy samples and excised glands. Sixty-seven patients with stage A or B adenocarcinoma of the prostate gland who had previously undergone 18-gauge core biopsy, who underwent radical prostatectomies, were studied. The Gleason score was determined by referred consensus among three pathologists. There was exact agreement between biopsy and excision in 39 cases (58%), whereas 24 cases (36%) differed by one digit. Three cases (4.5%) were undergraded, and one case (1.5%) was overgraded by two or more points. Only six tumors (8.9%) would have been incorrectly specified by the degree of differentiation. Discrepancies in grade of two points or more were not more frequent in cases with a small tumor volume (< or = 10%) in the biopsy specimens. We concluded that with careful histologic evaluation, the grade of tumor identified in these smaller biopsy cores correlates well with that seen at prostatectomy.

Bone marrow metastases from small cell cancer of the head and neck.

BACKGROUND: Primary small cell carcinoma of the head and neck is rare. Although the larynx is the most prevalent site of head and neck small cell carcinoma (SCC), this report will concentrate on SCC of the major salivary glands and paranasal sinuses. In all, 33 cases of paranasal sinus and 43 cases of major salivary gland SCC have been reported in the literature. METHODS: We report two patients, one with submandibular gland SCC and the other with maxillary sinus SCC. A literature review of all known paranasal sinus and major salivary gland SCC with inclusion of data from these two new cases is undertaken. Discussion of all past and present cases concentrates on sites of metastasis, treatment, and survival. RESULTS: Paranasal sinus SCCs predominantly arise from the nasal cavity, whereas the parotid gland is the primary site in three fourths of major salivary gland SCCs. One half of major salivary gland and three fourths of paranasal sinus SCCs have only local disease at presentation. Both patients in this report developed bone marrow metastases, a feature heretofore not observed in SCC from these primary sites. The patient with maxillary sinus SCC developed the syndrome of inappropriate antidiuretic hormone (SIADH). CONCLUSION: The paranasal sinus and major salivary glands are rare primary sites for SCCs. Long-term survival with local therapy in patients with local disease can occur, but in patients with metastatic disease survival mirrors metastatic pulmonary SCC.

Proliferating cell nuclear antigen in prostatic adenocarcinoma: correlation with established prognostic indicators.

OBJECTIVE: The utility of an antibody to proliferating cell nuclear antigen (PCNA), a growth-specific nuclear protein, was assessed as a prognostic variable for prostatic adenocarcinoma. Its expression was correlated with established prognostic indicators, including tumor grade, stage, prostatic-specific antigen (PSA), and percent of tumor in the gland at excision. METHODS: Forty archival needle biopsies containing a minimum of four hundred tumor cells were analyzed. Immunoperoxidase staining of paraffin sections was performed for PCNA (PC10) after pretreatment in antigen retrieval solution. A proliferative index (PI) for each case was derived using image analysis with measurement of at least four hundred twenty-five nuclei. RESULTS: PI values ranged from 2.4 to 31.3 percent. Mean PI values varied significantly (ANOVA, p = 0.005) among cases with dominant Gleason grade (DGG) of 3 (mean PI = 9.3%), 4 (mean PI = 13.7%), and 5 (mean PI = 18.8%). By t test, significant differences were noted for PI in cases with DGG 2 and 3 versus those with DGG 4 and 5 (p = 0.0065). PI for cases with DGG 3 versus 5 showed significant difference (p = 0.0017). Tumors of Gleason scores 5 to 7 differed significantly from those with scores 8 to 10 (p = 0.014). A statistical relationship for PI and PSA, clinical stage, and percent tumor at resection could not be established by linear regression. CONCLUSIONS: These findings suggest that additional study of the PI, as determined by PCNA immunohistochemistry and image analysis, may be warranted to determine its usefulness as an adjunctive parameter in prostate adenocarcinoma. This technique may be particularly useful in needle biopsies where limited tumor may render assessment of grade difficult.