The Reporting and Methodological Quality of Systematic Reviews Underpinning Clinical Practice Guidelines Focused on the Management of Cutaneous Melanoma: Cross-Sectional Analysis

BACKGROUND

Clinical practice guidelines (CPGs) inform evidence-based decision-making in the clinical setting; however, systematic reviews (SRs) that inform these CPGs may vary in terms of reporting and methodological quality, which affects confidence in summary effect estimates.

OBJECTIVE

Our objective was to appraise the methodological and reporting quality of the SRs used in CPGs for cutaneous melanoma and evaluate differences in these outcomes between Cochrane and non-Cochrane reviews.

METHODS

We conducted a cross-sectional analysis by searching PubMed for cutaneous melanoma guidelines published between January 1, 2015, and May 21, 2021. Next, we extracted SRs composing these guidelines and appraised their reporting and methodological rigor using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and AMSTAR (A Measurement Tool to Assess Systematic Reviews) checklists. Lastly, we compared these outcomes between Cochrane and non-Cochrane SRs. All screening and data extraction occurred in a masked, duplicate fashion.

RESULTS

Of the SRs appraised, the mean completion rate was 66.5% (SD 12.29%) for the PRISMA checklist and 44.5% (SD 21.05%) for AMSTAR. The majority of SRs (19/50, 53%) were of critically low methodological quality, with no SRs being appraised as high quality. There was a statistically significant association (P<.001) between AMSTAR and PRISMA checklists. Cochrane SRs had higher PRISMA mean completion rates and higher methodological quality than non-Cochrane SRs.

CONCLUSIONS

SRs supporting CPGs focused on the management of cutaneous melanoma vary in reporting and methodological quality, with the majority of SRs being of low quality. Increasing adherence to PRISMA and AMSTAR checklists will likely increase the quality of SRs, thereby increasing the level of evidence supporting cutaneous melanoma CPGs.

Contact inhibition and malignancy

The role of contact inhibition in influencing the behaviour of malignant cells is discussed in a review. Although tissue culture cannot simulate the immense complexity of the conditions in vivo, some of the distinctive features of malignant invasion can be conveniently observed with this technique. The evidence derived from this technique indicates that defective contact inhibition of movement of malignant cells does contribute to their invasiveness.

Contact reactions influencing cell locomotion of a mouse sarcoma in culture

An investigation of the behaviour of cells of the mouse transplantable sarcoma S180 in culture by time-lapse cinematography has been made to determine how the spreading of a population from an explant is affected by contact reactions between the sarcoma cells; and how the invasion of a fibroblast population is affected by contact reactions with the fibroblasts. Although the sarcoma cells show a form of contact inhibition to each other, this has little influence on the spreading of a population, which is brought about very largely by diffusive movement, in sharp contrast to the spreading of a fibroblast population. The invasion of a fibroblast population by S180 cells takes place as a consequence of defective contact inhibition; though contact inhibition (but not contact paralysis) of the S180 cells has an appreciable incidence. During invasion the S180 cells, though moving on the exposed surfaces of the fibroblasts, may be largely using the collagen substratum between the fibroblasts for their locomotion. The arrangement of the fibroblasts produces some degree of contact guidance of the sarcoma cells.

Fibroblasts

Images

Concepts in morphogenesis

The idea is now widely accepted that active cell locomotion is an important mechanism in many kinds of animal morphogenesis. The history of the idea suggests, however, that there was a peculiarly strong resistance to its acceptance. The resistance was not overtly expressed, but localized cell multiplication was nearly always preferred in explanations of morphogenesis. It is argued that, by the end of the nineteenth century, the knowledge existed that should have encouraged interpretation of many embryonic events in terms of cell locomotion. It did not do so, and in the history of other branches of development biology a similar reluctance to entertain the idea is discernible. It can be illustrated from studies of tissue culture and of malignant invasion. Some speculations about the nature of this temporary blind spot are discussed.

Invasive behavior between sarcoma and fibroblast populations in cell culture

The mutual invasion in culture of a population of standard fibroblasts (chick embryo) and a population of cells from a transplantable mouse sarcoma (MC)M, BAS/56, or 311) or of neontal mouse fibroblasts has been estimated quantitatively. We arranged the confrontation of the pairs of populations by placing primary explants near each other. After fixation, the distance the cells had migrated from each explant was sampled in the space between the explants where they met and at the sides of the explants where they migrated freely. Measurements of nuclear overlap and orientation were also made. In the sarcoma as in the fibroblast population, homologous contact inhibition of movement probably produced an oriented migration from the explants before the populations met. Abot 12-24 hours after, mutual invasion was considerably greater in the sarcoma versus fibroblast than in the fibroblast versus fibroblast experiments. It is proposed that this difference was due to a difference of heterologous contact inhibition in the two types of experiment.

The monolayering in tissue culture of fibroblasts from different sources

Cultures, predominantly of fibroblasts, were prepared from embryonic chick heart, new ­born mouse skeletal muscle and adult guinea-pig subcutaneous granuloma. The tissues were dissociated with trypsin, and secondary cultures made on a glass surface of each tissue separately and of two mixtures (chick and mouse; chick and guinea-pig). The monolayering of these cultures, which it is believed is largely due to contact inhibition, was assessed quantitatively after 24 h by means of an overlap index. Homologous indices (overlapping of like cells) were obtained for all cultures, and heterologous indices (overlapping of unlike cells) for the mixed cultures. When cultured separately the different tissues differed considerably in their overlap indices. Increasing local density of population appears to make contiguous cells more ready to overlap each other. In the mixed cultures the homologous overlap indices had often distinctly different values from those of the single-tissue experiments. It is evident that the nature as well as the density of the immediately surrounding cell population affects the chance that an overlap will occur between any pair of cells in contact. The heterologous overlap index in the mixed cultures was in one case lower than either of the homologous indices; in the other case it was intermediate between the homologous indices, though not significantly different from the smaller one. It seems therefore unlikely that any simple generalization about overlap frequency, which will predict the results of un tested combinations, will be possible. The mitotic index and nuclear area (probably representing degree of cell flattening) were also recorded, and in some cases, like the overlap index, showed variations according to the nature and density of the immediately surrounding cell population.

Long-term Changes in the Size and Collagen Content of Scars in the Skin of Rats

A Previous paper (Abercrombie, Flint, & James, 1954) described the early changes in size and collagen content of the granulation tissue and subsequent scar that fill a small wound made in the dorsal skin of a rat. The observations were carried up to the 25th day after wounding. It was found that by about the 10th day the wound had contracted down to a minimal area and wet weight, and that it remained at or near this minimum during the remaining 15 days of observation. The collagen content of the repair tissue increased during the phase of contraction and continued to do so in the completely contracted wound. In the present paper we describe the later evolution of the scar up to 300 days after wounding. The reduced area and wet weight reached by 10 days have proved to be merely temporary minima.

Wound Contraction in Relation to Collagen Formation in Scorbutic Guinea-pigs

A Wound in any mobile part of the skin of a mammal diminishes in area as it heals by a centripetal movement of the undamaged skin surrounding it. This movement, usually called wound contraction, depends on a pull exerted by the material within the wound (Lindquist, 1946; Abercrombie, Flint, & James, 1954; Billingham & Medawar, 1955). It is commonly believed that the effective force is developed by the newly formed collagen fibres. In a previous paper, however (Abercrombie, Flint, & James, 1954), we found that the course of the contraction of skin wounds in rats did not parallel the deposition of new collagen, chemically measured. This result, while certainly in no way conclusive by itself, suggested that the supposed role of collagen in contraction ought to be tested more stringently. This we have now done by measuring wounds made on guinea-pigs receiving a diet devoid of ascorbic acid.

Collagen Formation and Wound Contraction during Repair of Small Excised Wounds in the Skin of Rats

During the healing of an open wound in the loose skin of a mammal there occurs a conspicuous diminution of wound size, the result of a centripetal movement of the whole thickness of the surrounding skin, with a corresponding shrinkage of the wound content. This ‘wound contraction’ is distinct from the process of epithelialization. Many authors (e.g. v. Gaza, 1918; Lindquist, 1946) have supposed that wound contraction is in some way causally related to the process of collagen formation, which is simultaneously occurring in the wounded area. The investigation of this supposed relation requires a more exact quantitative picture of collagen formation in skin wounds than is at present available from histological studies (such as those of Dann, Glücksmann, & Tansley, 1941; Hunt, 1941; Lindquist, 1946) or from investigations of changes in tensile strength (such as those of Howes, Sooy, & Harvey, 1929; Botsford, 1941).

The Effects in Chick Blastoderms of replacing the Primitive Node by a Graft of Posterior Primitive Streak

In chick embryos with a full-length primitive streak the primitive node has been replaced by a graft from the posterior end of the primitive streak, and the blastoderm subsequently cultivated by Waddington’s technique for 24 hours. More than half of those embryos which developed at all showed a doubling of the anterior part of the axis, variable in extent but considerably exceeding the original extent of the graft, with convergence to a single posterior part. Prechordal head, parachordal mesoderm, and neural plate were affected by the doubling. Most specimens had two notochords fusing posteriorly into a single one, or occasionally terminating independently at a common primitive streak. Other specimens had a notochord in only one of the two axes, or in neither. Marking experiments with phosphorus32 on a few specimens showed that the graft, which had become greatly elongated, contributed the mesoderm between the notochords, but did not form any notochordal tissue. The doubled axes were often asymmetrical, and in the head region probably incomplete. The total amount of neural and notochordal tissue in a doubled embryo was not significantly different in volume from that in a single embryo. In a few specimens in which the axis remained single the place of the notochord was taken by side-plate mesoderm, probably graft-derived. Posteriorly this midline mesoderm became somitic. The neural plate in such specimens was little if at all reduced. Other specimens failed to heal and developed a split axis. They were usually devoid of notochord, but occasionally had a notochord along one side of the split, or along both sides. Finally, a few specimens formed an almost normal single axis.